1
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Zhang D. Photochemistry of Photoinduced-Reaction Generated Bubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:10085-10097. [PMID: 38695766 DOI: 10.1021/acs.langmuir.4c00254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2024]
Abstract
UV light can create and grow bubbles (herein referred to as PIRGBs for photoinduced-reaction generated bubbles) at liquid/solid interfaces through photoinduced reactions that produce gases. Unlike the simple experience of blowing water bubbles through a straw, in which the bubbles quickly move away from their nucleation sites, not only can a deep UV laser beam create PIRGBs in liquid acetone, but also can hold and grow them. Free bubbles could be attracted to the excitation region from millimeters away, indicating that the reactions cause radial inward flow on the liquid surface. The radial flow can be due to imbalanced surface tensions at the interfaces. Raman measurements reveal that the gases in the PIRGBs include C2H6, CO, and H2, and in liquid acetone, sp2-carbon species are detected upon the UV excitation. Time series Raman measurement discloses a photocarbonization process in which small acyclic carbon species gradually form small clusters with carbon rings and eventually produce a large piece of amorphous carbon at the top of a PIRGB in pure liquid acetone. The photocarbonization may open new avenues for development of carbonaceous materials. Using PIRGB, miniature or microscale gas production reactors can be developed for producing gases.
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Affiliation(s)
- Dianwen Zhang
- Microscopy Suite, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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2
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Abma G, Parkes MA, Razmus WO, Zhang Y, Wyatt AS, Springate E, Chapman RT, Horke DA, Minns RS. Direct Observation of a Roaming Intermediate and Its Dynamics. J Am Chem Soc 2024; 146:12595-12600. [PMID: 38682306 PMCID: PMC11082896 DOI: 10.1021/jacs.4c01543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 05/01/2024]
Abstract
Chemical reactions are often characterized by their transition state, which defines the critical geometry the molecule must pass through to move from reactants to products. Roaming provides an alternative picture, where in a dissociation reaction, the bond breaking is frustrated and a loosely bound intermediate is formed. Following bond breaking, the two partners are seen to roam around each other at distances of several Ångstroms, forming a loosely bound, and structurally ill-defined, intermediate that can subsequently lead to reactive or unreactive collisions. Here, we present a direct and time-resolved experimental measurement of roaming. By measuring the photoelectron spectrum of UV-excited acetaldehyde with a femtosecond extreme ultraviolet pulse, we captured spectral signatures of all of the key reactive structures, including that of the roaming intermediate. This provided a direct experimental measurement of the roaming process and allowed us to identify the time scales by which the roaming intermediate is formed and removed and the electronic potential surfaces upon which roaming proceeds.
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Affiliation(s)
- Grite
L. Abma
- Institute
for Molecules and Materials, Radboud University, Heijendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Michael A. Parkes
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Weronika O. Razmus
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K.
| | - Yu Zhang
- Central
Laser Facility, STFC Rutherford Appleton
Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Adam S. Wyatt
- Central
Laser Facility, STFC Rutherford Appleton
Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Emma Springate
- Central
Laser Facility, STFC Rutherford Appleton
Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Richard T. Chapman
- Central
Laser Facility, STFC Rutherford Appleton
Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Daniel A. Horke
- Institute
for Molecules and Materials, Radboud University, Heijendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Russell S. Minns
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K.
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3
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Li Z, Fu YL, Luo Z, Yang S, Wu Y, Wu H, Wu G, Zhang W, Fu B, Yuan K, Zhang D, Yang X. Roaming in highly excited states: The central atom elimination of triatomic molecule decomposition. Science 2024; 383:746-750. [PMID: 38359138 DOI: 10.1126/science.adn3357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 01/18/2024] [Indexed: 02/17/2024]
Abstract
Chemical reactions are generally assumed to proceed from reactants to products along the minimum energy path (MEP). However, straying from the MEP-roaming-has been recognized as an unconventional reaction mechanism and found to occur in both the ground and first excited states. Its existence in highly excited states is however not yet established. We report a dissociation channel to produce electronically excited fragments, S(1D)+O2(a1Δg), from SO2 photodissociation in highly excited states. The results revealed two dissociation pathways: One proceeds through the MEP to produce vibrationally colder O2(a1Δg) and the other yields vibrationally hotter O2(a1Δg) by means of a roaming pathway involving an intramolecular O abstraction during reorientation motion. Such roaming dynamics may well be the rule rather than the exception for molecular photodissociation through highly excited states.
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Affiliation(s)
- Zhenxing Li
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Yan-Lin Fu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Zijie Luo
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- Marine Engineering College, Dalian Maritime University, Liaoning 116026, P. R. China
| | - Shuaikang Yang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Yucheng Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Hao Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guorong Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Weiqing Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Bina Fu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Hefei National Laboratory, Hefei 230088, P. R. China
| | - Kaijun Yuan
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Hefei National Laboratory, Hefei 230088, P. R. China
| | - Donghui Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Hefei National Laboratory, Hefei 230088, P. R. China
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- Department of Chemistry and Center for Advanced Light Source Research, College of Science, Southern University of Science and Technology, Shenzhen 518055, P. R. China
- Hefei National Laboratory, Hefei 230088, P. R. China
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4
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Kokoouline V, Alijah A, Tyuterev V. Lifetimes and decay mechanisms of isotopically substituted ozone above the dissociation threshold: matching quantum and classical dynamics. Phys Chem Chem Phys 2024; 26:4614-4628. [PMID: 38251711 DOI: 10.1039/d3cp04286c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
Energies and lifetimes of vibrational resonances were computed for 18O-enriched isotopologue 50O3 = {16O16O18O and 16O18O16O} of the ozone molecule using hyperspherical coordinates and the method of complex absorbing potential. Various types of scattering resonances were identified, including roaming OO-O rotational states, the series corresponding to continuation of bound vibrational resonances of highly excited bending or symmetric stretching vibrational modes. Such a series become metastable above the dissociation limit. The coupling between the vibrationally excited O2 fragment and rotational roaming gives rise to Feshbach type resonances in ozone. Different paths for the formation and decay of symmetric 16O18O16O and asymmetric species 16O16O18O were also identified. The symmetry properties of the total rovibronic wave functions of the 18O-enriched isotopologues are discussed in the context of allowed dissociation channels.
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Affiliation(s)
| | - Alexander Alijah
- Groupe de Spectrometrie Moléculaire et Atmospherique, UMR CNRS 7331, University of Reims Champagne-Ardenne, Reims Cedex 2, F-51687, France
| | - Vladimir Tyuterev
- Laboratory of Molecular Quantum Mechanics and Radiative transfer, Tomsk State University, Tomsk, Russia
- Laboratory of Theoretical Spectroscopy, V.E. Zuev Institute of Atmospheric Optics, Russian Academy of Sciences, Tomsk, 634055, Russia
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5
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Pu M, Nielsen CDT, Senol E, Sperger T, Schoenebeck F. Post-Transition-State Dynamic Effects in the Transmetalation of Pd(II)-F to Pd(II)-CF 3. JACS AU 2024; 4:263-275. [PMID: 38274253 PMCID: PMC10806791 DOI: 10.1021/jacsau.3c00724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 01/27/2024]
Abstract
The observation of post-transition-state dynamic effects in the context of metal-based transformation is rare. To date, there has been no reported case of a dynamic effect for the widely employed class of palladium-mediated coupling reactions. We performed an experimental and computational study of the trifluoromethylation of Pd(II)F, which is a key step in the Pd(0)/Pd(II)-catalyzed trifluoromethylation of aryl halides or acid fluorides. Our experiments show that the cis/trans speciation of the formed Pd(II)CF3 is highly solvent- and transmetalation reagent-dependent. We employed GFN2-xTB- and B3LYP-D3-based molecular dynamics trajectory calculations (with and without explicit solvation) along with high-level QM calculations and found that depending on the medium, different transmetalation mechanisms appear to be operative. A statistically representative number of Born-Oppenheimer molecular dynamics (MD) simulations suggest that in benzene, a difluorocarbene is generated in the transmetalation with R3SiCF3, which subsequently recombines with the Pd via two distinct pathways, leading to either the cis- or trans-Pd(II)CF3. Conversely, GFN2-xTB simulations in MeCN suggest that in polar/coordinating solvents an ion-pair mechanism is dominant. A CF3 anion is initially liberated and then rebinds with the Pd(II) cation to give a cis- or trans-Pd(II). In both scenarios, a single transmetalation transition state gives rise to both cis- and trans-species directly, owing to bifurcation after the transition state. The potential subsequent cis- to trans isomerization of the Pd(II)CF3 was also studied and found to be strongly inhibited by free phosphine, which in turn was experimentally identified to be liberated through displacement by a polar/coordinating solvent from the cis-Pd(II)CF3 complex. The simulations also revealed how the variation of the Pd-coordination sphere results in divergent product selectivities.
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Affiliation(s)
- Maoping Pu
- Institute of Organic Chemistry,
RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | | | - Erdem Senol
- Institute of Organic Chemistry,
RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Theresa Sperger
- Institute of Organic Chemistry,
RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Franziska Schoenebeck
- Institute of Organic Chemistry,
RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
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6
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Robinson MS, Küpper J. Unraveling the ultrafast dynamics of thermal-energy chemical reactions. Phys Chem Chem Phys 2024; 26:1587-1601. [PMID: 38131437 DOI: 10.1039/d3cp03954d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
In this perspective, we discuss how one can initiate, image, and disentangle the ultrafast elementary steps of thermal-energy chemical dynamics, building upon advances in technology and scientific insight. We propose that combinations of ultrashort mid-infrared laser pulses, controlled molecular species in the gas phase, and forefront imaging techniques allow to unravel the elementary steps of general-chemistry reaction processes in real time. We detail, for prototypical first reaction systems, experimental methods enabling these investigations, how to sufficiently prepare and promote gas-phase samples to thermal-energy reactive states with contemporary ultrashort mid-infrared laser systems, and how to image the initiated ultrafast chemical dynamics. The results of such experiments will clearly further our understanding of general-chemistry reaction dynamics.
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Affiliation(s)
- Matthew S Robinson
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jochen Küpper
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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7
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Severt T, Weckwerth E, Kaderiya B, Feizollah P, Jochim B, Borne K, Ziaee F, P KR, Carnes KD, Dantus M, Rolles D, Rudenko A, Wells E, Ben-Itzhak I. Initial-site characterization of hydrogen migration following strong-field double-ionization of ethanol. Nat Commun 2024; 15:74. [PMID: 38168047 PMCID: PMC10761976 DOI: 10.1038/s41467-023-44311-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 12/05/2023] [Indexed: 01/05/2024] Open
Abstract
An essential problem in photochemistry is understanding the coupling of electronic and nuclear dynamics in molecules, which manifests in processes such as hydrogen migration. Measurements of hydrogen migration in molecules that have more than two equivalent hydrogen sites, however, produce data that is difficult to compare with calculations because the initial hydrogen site is unknown. We demonstrate that coincidence ion-imaging measurements of a few deuterium-tagged isotopologues of ethanol can determine the contribution of each initial-site composition to hydrogen-rich fragments following strong-field double ionization. These site-specific probabilities produce benchmarks for calculations and answer outstanding questions about photofragmentation of ethanol dications; e.g., establishing that the central two hydrogen atoms are 15 times more likely to abstract the hydroxyl proton than a methyl-group proton to form H[Formula: see text] and that hydrogen scrambling, involving the exchange of hydrogen between different sites, is important in H2O+ formation. The technique extends to dynamic variables and could, in principle, be applied to larger non-cyclic hydrocarbons.
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Affiliation(s)
- Travis Severt
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Eleanor Weckwerth
- Department of Physics, Augustana University, Sioux Falls, SD, 57108, USA
| | - Balram Kaderiya
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Peyman Feizollah
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Bethany Jochim
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Kurtis Borne
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Farzaneh Ziaee
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Kanaka Raju P
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
- School of Quantum Technology, DIAT (DU), Pune, Maharashtra, 411025, India
| | - Kevin D Carnes
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Marcos Dantus
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Daniel Rolles
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Artem Rudenko
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Eric Wells
- Department of Physics, Augustana University, Sioux Falls, SD, 57108, USA.
| | - Itzik Ben-Itzhak
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA.
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8
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Klippenstein SJ, Elliott SN. OH Roaming during the Ozonolysis of α-Pinene: A New Route to Highly Oxygenated Molecules? J Phys Chem A 2023; 127:10647-10662. [PMID: 38055299 DOI: 10.1021/acs.jpca.3c05179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
The formation of low-volatility organic compounds in the ozonolysis of α-pinene, the dominant atmospheric monoterpene, provides an important route to aerosol formation. In this work, we consider a previously unexplored set of pathways for the formation of highly oxygenated molecules in α-pinene ozonolysis. Pioneering, direct experimental observations of Lester and co-workers have demonstrated a significant production of hydroxycarbonyl products in the dissociation of Criegee intermediates. Theoretical analyses indicate that this production arises from OH roaming-induced pathways during the OO fission of the vinylhydroperoxides (VHPs), which in turn come from internal H transfers in the Criegee intermediates. Ab initio kinetics computations are used here to explore the OH roaming-induced channels that arise from the ozonolysis of α-pinene. For computational reasons, the calculations consider a surrogate for α-pinene, where two spectator methyl groups are replaced with H atoms. Multireference electronic structure calculations are used to illustrate a variety of energetically accessible OH roaming pathways for the four VHPs arising from the ozonolysis of this α-pinene surrogate. Ab initio transition-state theory-based master equation calculations indicate that for the dissociation of stabilized VHPs, these OH roaming pathways are kinetically significant with a branching that generally increases from ∼20% at room temperature up to ∼70% at lower temperatures representative of the troposphere. For one of the VHPs, this branching already exceeds 60% at room temperature. For the overall ozonolysis process, these branching ratios would be greatly reduced by a limited branching to the stabilized VHP, although there would also be some modest roaming fraction for the nonthermal VHP dissociation process. The strong exothermicities of the roaming-induced isomerizations/additions and abstractions suggest new routes to fission of the cyclobutane rings. Such ring fissions would facilitate further autoxidation reactions, thereby providing a new route for producing highly oxygenated nonvolatile precursors to aerosol formation.
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Affiliation(s)
- Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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9
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Wu H, Fu Y, Fu B, Zhang DH. Roaming Dynamics in Hydroxymethyl Hydroperoxide Decomposition Revealed by the Full-Dimensional Potential Energy Surface of the CH 2OO + H 2O Reaction. J Phys Chem A 2023; 127:9098-9105. [PMID: 37870501 DOI: 10.1021/acs.jpca.3c05818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
The CH2OO + H2O reaction is an important atmospheric process that leads to the formation of formic acid (HCOOH) and water via the intermediate hydroxymethyl hydroperoxide (HOCH2OOH, HMHP). We investigated the intricacies of this process by employing quasiclassical trajectory calculations on an accurate, full-dimensional ab initio potential energy surface (PES). In addition to the direct mechanism via the transition state (TS), an interesting roaming mechanism was found to play the predominant role in producing H2O and HCOOH. This roaming pathway is featured as the near direct dissociation of HMHP into OH and hydroxymethoxy radical, followed by the retraction of OH and abstraction of the H atom, culminating in the formation of H2O. Due to the longer interaction time of the roaming mechanism, less product translational energy was released, but more internal energies of HCOOH were obtained, as compared with the direct TS mechanism. The enhanced yield of H2O and formic acid achieved through roaming dynamics underscores the significance of dynamics simulations based on an accurate full-dimensional PES. This work provides new insights into the dynamics of the CH2OO + H2O reaction and its implications for atmospheric chemistry.
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Affiliation(s)
- Hao Wu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanlin Fu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Bina Fu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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10
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Liu R, Zhang Z, Yan L, Yang X, Zhu Y, Su P, Song H, Wang Z. The Influence of Hydrogen Bonds on the Roaming Reaction. J Phys Chem Lett 2023; 14:9351-9356. [PMID: 37820388 DOI: 10.1021/acs.jpclett.3c02133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Roaming bypasses the conventional transition state and is a significant reaction pathway due to the unusual energy distributions of its products; however, its reaction pathway under external environmental interactions remains unclear. Herein, we report for the first time the roaming process of nitrobenzene, which is influenced by the hydrogen bonds (H-bonds) between nitro- and phenyl radicals and water molecules in the gas phase. Notably, despite the fact that the single water structure produces a higher but narrower barrier, whereas the double water structure leads to a lower but wider barrier, the roaming reaction still occurs. The underlying mechanism responsible for these influences of H-bonds is ascribed to the dramatically changed polarization and correlation interactions between the roaming radicals. The reaction rates and thermal perturbation probabilities are also remarkably influenced due to the presence of the H-bonds, by approximately 2 orders of magnitude. It is anticipated that this work will encourage the promising feasibility of introducing environmental molecules to modulate the roaming reaction.
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Affiliation(s)
- Rui Liu
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, China
| | - Zhiyuan Zhang
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Longxiang Yan
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Xinrui Yang
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
| | - Yu Zhu
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
- College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158, China
| | - Peifeng Su
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Huajie Song
- Beijing Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
| | - Zhigang Wang
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, China
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China
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11
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Welsh BA, Corrigan ME, Assaf E, Nauta K, Sebastianelli P, Jordan MJT, Fittschen C, Kable SH. Photophysical oxidation of HCHO produces HO 2 radicals. Nat Chem 2023; 15:1350-1357. [PMID: 37414879 DOI: 10.1038/s41557-023-01272-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 06/07/2023] [Indexed: 07/08/2023]
Abstract
Formaldehyde, HCHO, is the highest-volume carbonyl in the atmosphere. It absorbs sunlight at wavelengths shorter than 330 nm and photolyses to form H and HCO radicals, which then react with O2 to form HO2. Here we show HCHO has an additional HO2 formation pathway. At photolysis energies below the energetic threshold for radical formation we directly detect HO2 at low pressures by cavity ring-down spectroscopy and indirectly detect HO2 at 1 bar by Fourier-transform infrared spectroscopy end-product analysis. Supported by electronic structure theory and master equation simulations, we attribute this HO2 to photophysical oxidation (PPO): photoexcited HCHO relaxes non-radiatively to the ground electronic state where the far-from-equilibrium, vibrationally activated HCHO molecules react with thermal O2. PPO is likely to be a general mechanism in tropospheric chemistry and, unlike photolysis, PPO will increase with increasing O2 pressure.
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Affiliation(s)
- Blair A Welsh
- School of Chemistry, University of New South Wales, Kensington, New South Wales, Australia
- Combustion Research Facility, Sandia National Laboratories, Livermore, CA, USA
| | - Maggie E Corrigan
- School of Chemistry, University of Sydney, Sydney, New South Wales, Australia
| | - Emmanuel Assaf
- Université Lille, CNRS, UMR 8522, PC2A-Physicochimie des Processus de Combustion et de l'Atmosphère, Lille, France
- Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Klaas Nauta
- School of Chemistry, University of New South Wales, Kensington, New South Wales, Australia
| | - Paolo Sebastianelli
- School of Chemistry, University of New South Wales, Kensington, New South Wales, Australia
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, New South Wales, Australia
| | - Meredith J T Jordan
- School of Chemistry, University of Sydney, Sydney, New South Wales, Australia.
| | - Christa Fittschen
- Université Lille, CNRS, UMR 8522, PC2A-Physicochimie des Processus de Combustion et de l'Atmosphère, Lille, France
| | - Scott H Kable
- School of Chemistry, University of New South Wales, Kensington, New South Wales, Australia.
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12
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Guan Y, Xie C, Guo H, Yarkony DR. Toward a Unified Analytical Description of Internal Conversion and Intersystem Crossing in the Photodissociation of Thioformaldehyde. I. Diabatic Singlet States. J Chem Theory Comput 2023; 19:6414-6424. [PMID: 37698839 DOI: 10.1021/acs.jctc.3c00628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
The photodissociation of thioformaldehyde is an archetypal system for the study of competition between internal conversion and intersystem crossing, which involves its two singlet states (S0 and S1) and two triplet states (T1 and T2). In order to perform accurate dynamic simulations, either quantum or quasi-classical, it is essential to construct an analytical representation for all necessary electronic structure data. In this work, a diabatic potential energy matrix (DPEM), Hd, for the two singlet states (S0 and S1) is reported. The analytical form of DPEM is symmetrized and constructed to reproduce adiabatic energies, energy gradients, and derivative couplings obtained from high-level multireference configuration interaction wave functions. The Hd is fully saturated in the molecular configuration space with a trajectory-guided point sampling approach. This Hd can provide the accurate description of the photodissociation of thioformaldehyde on its singlet states and is also a necessary part for incorporating the spin-orbit couplings into a unified diabatic framework. Preliminary quasi-classical trajectory simulations show that a roaming mechanism also exists in the molecular dissociation channel of thioformaldehyde.
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Affiliation(s)
- Yafu Guan
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Changjian Xie
- Institute of Modern Physics, Northwest University, Xi'an, Shaanxi 710069, People's Republic of China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - David R Yarkony
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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13
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Yang Y, Ren H, Zhang M, Zhou S, Mu X, Li X, Wang Z, Deng K, Li M, Ma P, Li Z, Hao X, Li W, Chen J, Wang C, Ding D. H 2 formation via non-Born-Oppenheimer hydrogen migration in photoionized ethane. Nat Commun 2023; 14:4951. [PMID: 37587115 PMCID: PMC10432507 DOI: 10.1038/s41467-023-40628-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 08/03/2023] [Indexed: 08/18/2023] Open
Abstract
Neutral H2 formation via intramolecular hydrogen migration in hydrocarbon molecules plays a vital role in many chemical and biological processes. Here, employing cold target recoil ion momentum spectroscopy (COLTRIMS) and pump-probe technique, we find that the non-adiabatic coupling between the ground and excited ionic states of ethane through conical intersection leads to a significantly high yield of neutral H2 fragment. Based on the analysis of fingerprints that are sensitive to orbital symmetry and electronic state energies in the photoelectron momentum distributions, we tag the initial electronic population of both the ground and excited ionic states and determine the branching ratios of H2 formation channel from those two states. Incorporating theoretical simulation, we established the timescale of the H2 formation to be ~1300 fs. We provide a comprehensive characterization of H2 formation in ionic states of ethane mediated by conical intersection and reveals the significance of non-adiabatic coupling dynamics in the intramolecular hydrogen migration.
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Affiliation(s)
- Yizhang Yang
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China
| | - Hao Ren
- Institute of Theoretical Physics and Department of Physics, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, China
| | - Ming Zhang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Shengpeng Zhou
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China
| | - Xiangxu Mu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Xiaokai Li
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China
| | - Zhenzhen Wang
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China
| | - Ke Deng
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China
| | - Mingxuan Li
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China
| | - Pan Ma
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China
| | - Zheng Li
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, 100871, Beijing, China.
- Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, Shanxi, China.
- Peking University Yangtze Delta Institute of Optoelectronics, 226010, Nantong, Jiangsu, China.
| | - Xiaolei Hao
- Institute of Theoretical Physics and Department of Physics, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, China.
| | - Weidong Li
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, and College of Engineering Physics, Shenzhen Technology University, 518118, Shenzhen, China
| | - Jing Chen
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, and College of Engineering Physics, Shenzhen Technology University, 518118, Shenzhen, China
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, Department of Modern Physics, University of Science and Technology of China, 230026, Hefei, China
| | - Chuncheng Wang
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China.
| | - Dajun Ding
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, 130012, Changchun, China.
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14
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Guerrero-Méndez L, Lema-Saavedra A, Jiménez E, Fernández-Ramos A, Martínez-Núñez E. Gas-phase formation of glycolonitrile in the interstellar medium. Phys Chem Chem Phys 2023; 25:20988-20996. [PMID: 37503548 DOI: 10.1039/d3cp02379f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Our automated reaction discovery program, AutoMeKin, has been utilized to investigate the formation of glycolonitrile (HOCH2CN) in the gas phase under the low temperatures of the interstellar medium (ISM). The feasibility of a proposed pathway depends on the absence of barriers above the energy of reactants and the availability of the suggested precursors in the ISM. Based on these criteria, several radical-radical reactions and a radical-molecule reaction have been identified as viable formation routes in the ISM. Among the radical-radical reactions, OH + CH2CN appears to be the most relevant, considering the energy of the radicals and its ability to produce glycolonitrile in a single step. However, our analysis reveals that this reaction produces hydrogen isocyanide (HNC) and formaldehyde (CH2O), with rate coefficients ranging from (7.3-11.5) × 10-10 cm3 molecule-1 s-1 across the temperature range of 10-150 K. Furthermore, the identification of this remarkably efficient pathway for HNC elimination from glycolonitrile significantly broadens the possibilities for any radical-radical mechanism proposed in our research to be considered as a feasible pathway for the formation of HNC in the ISM. This finding is particularly interesing given the persistently unexplained overabundance of hydrogen isocyanide in the ISM. Among the radical-molecule reactions investigated, the most promising one is OH + CH2CHNH, which forms glycolonitrile and atomic hydrogen with rate coefficients in the range (0.3-6.6) × 10-10 cm3 molecule-1 s-1 within the 10-150 K temperature range. Our calculations indicate that the formation of both hydrogen isocyanide and glycolonitrile is efficient under the harsh conditions of the ISM.
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Affiliation(s)
- Luis Guerrero-Méndez
- Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, Avda. das Ciencias s/n 15782, Santiago de Compostela, Spain.
| | - Anxo Lema-Saavedra
- Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidade de Santiago de Compostela, C/Jenaro de la Fuente s/n, 15782, Santiago de Compostela, Spain
| | - Elena Jiménez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1b, 13071, Ciudad Real, Spain
- Instituto de Investigación en Combustión y Contaminación Atmosférica (ICCA), Universidad de Castilla-La Mancha, Camino de Moledores s/n, 13071, Ciudad Real, Spain
| | - Antonio Fernández-Ramos
- Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, Avda. das Ciencias s/n 15782, Santiago de Compostela, Spain.
- Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidade de Santiago de Compostela, C/Jenaro de la Fuente s/n, 15782, Santiago de Compostela, Spain
| | - Emilio Martínez-Núñez
- Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, Avda. das Ciencias s/n 15782, Santiago de Compostela, Spain.
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15
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Chang Y, Ashfold MNR, Yuan K, Yang X. Exploring the vacuum ultraviolet photochemistry of astrochemically important triatomic molecules. Natl Sci Rev 2023; 10:nwad158. [PMID: 37771464 PMCID: PMC10533343 DOI: 10.1093/nsr/nwad158] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/03/2022] [Accepted: 02/08/2023] [Indexed: 09/30/2023] Open
Abstract
The recently constructed vacuum ultraviolet (VUV) free electron laser (FEL) at the Dalian Coherent Light Source (DCLS) is yielding a wealth of new and exquisitely detailed information about the photofragmentation dynamics of many small gas-phase molecules. This Review focuses particular attention on five triatomic molecules-H2O, H2S, CO2, OCS and CS2. Each shows excitation wavelength-dependent dissociation dynamics, yielding photofragments that populate a range of electronic and (in the case of diatomic fragments) vibrational and rotational quantum states, which can be characterized by different translational spectroscopy methods. The photodissociation of an isolated molecule from a well-defined initial quantum state provides a lens through which one can investigate how and why chemical reactions occur, and provides numerous opportunities for fruitful, synergistic collaborations with high-level ab initio quantum chemists. The chosen molecules, their photofragments and the subsequent chemical reaction networks to which they can contribute are all crucial in planetary atmospheres and in interstellar and circumstellar environments. The aims of this Review are 3-fold: to highlight new photochemical insights enabled by the VUV-FEL at the DCLS, notably the recently recognized central atom elimination process that is shown to contribute in all of these triatomic molecules; to highlight some of the potential implications of this rich photochemistry to our understanding of interstellar chemistry and molecular evolution within the universe; and to highlight other and future research directions in areas related to chemical reaction dynamics and astrochemistry that will be enabled by increased access to VUV-FEL sources.
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Affiliation(s)
- Yao Chang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | | | - Kaijun Yuan
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Hefei National Laboratory, Hefei 230088, China
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- Hefei National Laboratory, Hefei 230088, China
- Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen 518055, China
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16
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Wang E, Kling NG, LaForge AC, Obaid R, Pathak S, Bhattacharyya S, Meister S, Trost F, Lindenblatt H, Schoch P, Kübel M, Pfeifer T, Rudenko A, Díaz-Tendero S, Martín F, Moshammer R, Rolles D, Berrah N. Ultrafast Roaming Mechanisms in Ethanol Probed by Intense Extreme Ultraviolet Free-Electron Laser Radiation: Electron Transfer versus Proton Transfer. J Phys Chem Lett 2023; 14:4372-4380. [PMID: 37140167 DOI: 10.1021/acs.jpclett.2c03764] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Ultrafast H2+ and H3+ formation from ethanol is studied using pump-probe spectroscopy with an extreme ultraviolet (XUV) free-electron laser. The first pulse creates a dication, triggering H2 roaming that leads to H2+ and H3+ formation, which is disruptively probed by a second pulse. At photon energies of 28 and 32 eV, the ratio of H2+ to H3+ increases with time delay, while it is flat at a photon energy of 70 eV. The delay-dependent effect is ascribed to a competition between electron and proton transfer. High-level quantum chemistry calculations show a flat potential energy surface for H2 formation, indicating that the intermediate state may have a long lifetime. The ab initio molecular dynamics simulation confirms that, in addition to the direct emission, a small portion of H2 undergoes a roaming mechanism that leads to two competing pathways: electron transfer from H2 to C2H4O2+ and proton transfer from C2H4O2+ to H2.
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Affiliation(s)
- Enliang Wang
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Nora G Kling
- Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, United States
| | - Aaron C LaForge
- Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, United States
| | - Razib Obaid
- Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, United States
| | - Shashank Pathak
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
| | - Surjendu Bhattacharyya
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
| | - Severin Meister
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Florian Trost
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Hannes Lindenblatt
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Patrizia Schoch
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Matthias Kübel
- Institute of Optics and Quantum Electronics, Friedrich Schiller University Jena, D-07743 Jena, Germany
- Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany
| | - Thomas Pfeifer
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Artem Rudenko
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
| | - Sergio Díaz-Tendero
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Fernando Martín
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nano), Campus de Cantoblanco, 28049 Madrid, Spain
| | - Robert Moshammer
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Daniel Rolles
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
| | - Nora Berrah
- Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, United States
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17
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Yuan Y, Tsai P. Photodissociation dynamics of acetaldehyde at 267 nm: A computational study of the
CO
‐forming channels. J CHIN CHEM SOC-TAIP 2023. [DOI: 10.1002/jccs.202300036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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18
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He N, Huang M, Evangelista FA. CO Inversion on a NaCl(100) Surface: A Multireference Quantum Embedding Study. J Phys Chem A 2023; 127:1975-1987. [PMID: 36799901 PMCID: PMC9986868 DOI: 10.1021/acs.jpca.2c05844] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
We develop a multireference quantum embedding model to investigate a recent experimental observation of the isomerization of vibrationally excited CO molecules on a NaCl(100) surface [Science 2020, 367, 175-178]. To explore this mechanism, we built a reduced potential energy surface of CO interacting with NaCl(100) using a second-order multireference perturbation theory, modeling the adsorbate-surface interaction with our previously developed active space embedding theory (ASET). We considered an isolated CO molecule on NaCl(100) and a high-coverage CO monolayer (1/1), and for both we generated potential energy surfaces parametrized by the CO stretching, adsorption, and inversion coordinates. These surfaces are used to determine stationary points and adsorption energies and to perform a vibrational analysis of the states relevant to the inversion mechanism. We found that for near-equilibrium bond lengths, CO adsorbed in the C-down configuration is lower in energy than in the O-down configuration. Stretching of the C-O bond reverses the energetic order of these configurations, supporting the accepted isomerization mechanism. The vibrational constants obtained from these potential energy surfaces show a small (< 10 cm-1) blue- and red-shift for the C-down and O-down configurations, respectively, in agreement with experimental assignments and previous theoretical studies. Our vibrational analysis of the monolayer case suggests that the O-down configuration is energetically more stable than the C-down one beyond the 16th vibrational excited state of CO, a value slightly smaller than the one from quasi-classical trajectory simulations (22nd) and consistent with the experiment. Our analysis suggests that CO-CO interactions in the monolayer play an important role in stabilizing highly vibrationally excited states in the O-down configuration and reducing the barrier between the C-down and O-down geometries, therefore playing a crucial role in the inversion mechanism.
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Affiliation(s)
- Nan He
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Meng Huang
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Francesco A Evangelista
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
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19
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Käser S, Vazquez-Salazar LI, Meuwly M, Töpfer K. Neural network potentials for chemistry: concepts, applications and prospects. DIGITAL DISCOVERY 2023; 2:28-58. [PMID: 36798879 PMCID: PMC9923808 DOI: 10.1039/d2dd00102k] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022]
Abstract
Artificial Neural Networks (NN) are already heavily involved in methods and applications for frequent tasks in the field of computational chemistry such as representation of potential energy surfaces (PES) and spectroscopic predictions. This perspective provides an overview of the foundations of neural network-based full-dimensional potential energy surfaces, their architectures, underlying concepts, their representation and applications to chemical systems. Methods for data generation and training procedures for PES construction are discussed and means for error assessment and refinement through transfer learning are presented. A selection of recent results illustrates the latest improvements regarding accuracy of PES representations and system size limitations in dynamics simulations, but also NN application enabling direct prediction of physical results without dynamics simulations. The aim is to provide an overview for the current state-of-the-art NN approaches in computational chemistry and also to point out the current challenges in enhancing reliability and applicability of NN methods on a larger scale.
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Affiliation(s)
- Silvan Käser
- Department of Chemistry, University of Basel Klingelbergstrasse 80 CH-4056 Basel Switzerland
| | | | - Markus Meuwly
- Department of Chemistry, University of Basel Klingelbergstrasse 80 CH-4056 Basel Switzerland
| | - Kai Töpfer
- Department of Chemistry, University of Basel Klingelbergstrasse 80 CH-4056 Basel Switzerland
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20
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A quantum-classical correspondence in the dynamics around higher order saddle points: a Bohmian perspective. Theor Chem Acc 2023. [DOI: 10.1007/s00214-023-02957-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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21
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Campbell JS, Nauta K, Hansen CS, Kable SH. POPTARTS: A New Method to Determine Quantum Yields in a Molecular Beam. J Phys Chem A 2022; 126:9268-9275. [DOI: 10.1021/acs.jpca.2c06289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Affiliation(s)
- Jyoti S. Campbell
- School of Chemistry, University of New South Wales, Kensington, NSW2052, Australia
| | - Klaas Nauta
- School of Chemistry, University of New South Wales, Kensington, NSW2052, Australia
| | | | - Scott H. Kable
- School of Chemistry, University of New South Wales, Kensington, NSW2052, Australia
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22
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Cheng C, Singh V, Matsika S, Weinacht T. Strong Field Double Ionization of Formaldehyde Investigated Using Momentum Resolved Covariance Imaging and Trajectory Surface Hopping. J Phys Chem A 2022; 126:7399-7406. [PMID: 36178987 DOI: 10.1021/acs.jpca.2c04650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We use covariance velocity map imaging of fragment ions from the strong field double ionization of formaldehyde in conjunction with trajectory surface hopping calculations to determine the ionization yields to different singlet and triplet states of the dication. The calculated kinetic energy release for trajectories initiated on different electronic states is compared with the experimental values based on momentum resolved covariance measurements. We determine the state resolved double ionization yields as a function of laser intensity and pulse duration down to 6 fs (two optical cycles).
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Affiliation(s)
- Chuan Cheng
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York11794-3800, United States
| | - Vaibhav Singh
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania19122, United States
| | - Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania19122, United States
| | - Thomas Weinacht
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York11794-3800, United States
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23
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Peng T, Bai Y, Qi J, Fu YL, Han YC. Comparison of the supercollisions of the deuterium atom with acetylene and ethylene. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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24
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Lawrence JE, Richardson JO. Improved microcanonical instanton theory. Faraday Discuss 2022; 238:204-235. [PMID: 35929848 DOI: 10.1039/d2fd00063f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Canonical (thermal) instanton theory is now routinely applicable to complex gas-phase reactions and allows for the accurate description of tunnelling in highly non-separable systems. Microcanonical instanton theory is by contrast far less well established. Here, we demonstrate that the best established microcanonical theory [S. Chapman, B. C. Garrett and W. H. Miller, J. Chem. Phys., 1975, 63, 2710-2716], fails to accurately describe the deep-tunnelling regime for systems where the frequencies of the orthogonal modes change rapidly along the instanton path. By taking a first principles approach to the derivation of microcanonical instanton theory, we obtain an improved method, which accurately recovers the thermal instanton rate when integrated over energy. The resulting theory also correctly recovers the separable limit and can be thought of as an instanton generalisation of Rice-Ramsperger-Kassel-Marcus (RRKM) theory. When combined with the density-of-states approach [W. Fang, P. Winter and J. O. Richardson, J. Chem. Theory Comput., 2021, 17, 40-55], this new method can be straightforwardly applied to real molecular systems.
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25
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Westermayr J, Gastegger M, Vörös D, Panzenboeck L, Joerg F, González L, Marquetand P. Deep learning study of tyrosine reveals that roaming can lead to photodamage. Nat Chem 2022; 14:914-919. [PMID: 35655007 DOI: 10.1038/s41557-022-00950-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 04/13/2022] [Indexed: 01/12/2023]
Abstract
Amino acids are among the building blocks of life, forming peptides and proteins, and have been carefully 'selected' to prevent harmful reactions caused by light. To prevent photodamage, molecules relax from electronic excited states to the ground state faster than the harmful reactions can occur; however, such photochemistry is not fully understood, in part because theoretical simulations of such systems are extremely expensive-with only smaller chromophores accessible. Here, we study the excited-state dynamics of tyrosine using a method based on deep neural networks that leverages the physics underlying quantum chemical data and combines different levels of theory. We reveal unconventional and dynamically controlled 'roaming' dynamics in excited tyrosine that are beyond chemical intuition and compete with other ultrafast deactivation mechanisms. Our findings suggest that the roaming atoms are radicals that can lead to photodamage, offering a new perspective on the photostability and photodamage of biological systems.
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Affiliation(s)
- Julia Westermayr
- Faculty of Chemistry, Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria.,Department of Chemistry, University of Warwick, Coventry, UK
| | - Michael Gastegger
- Machine Learning Group, Technical University of Berlin, Berlin, Germany
| | - Dóra Vörös
- Faculty of Chemistry, Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Lisa Panzenboeck
- Faculty of Chemistry, Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria.,Faculty of Chemistry, Department of Analytical Chemistry, University of Vienna, Vienna, Austria
| | - Florian Joerg
- Faculty of Chemistry, Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria.,Faculty of Chemistry, Institute of Computational Biological Chemistry, University of Vienna, Vienna, Austria
| | - Leticia González
- Faculty of Chemistry, Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria.,Vienna Research Platform on Accelerating Photoreaction Discovery, University of Vienna, Vienna, Austria
| | - Philipp Marquetand
- Faculty of Chemistry, Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria. .,Vienna Research Platform on Accelerating Photoreaction Discovery, University of Vienna, Vienna, Austria. .,Research Network Data Science @ Uni Vienna, University of Vienna, Vienna, Austria.
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26
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Tantillo DJ. Portable Models for Entropy Effects on Kinetic Selectivity. J Am Chem Soc 2022; 144:13996-14004. [PMID: 35895875 DOI: 10.1021/jacs.2c04683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Differences in entropies of competing transition states can direct kinetic selectivity. Understanding and modeling such entropy differences at the molecular level is complicated by the fact that entropy is statistical in nature; i.e., it depends on multiple vibrational states of transition structures, the existence of multiple dynamically accessible pathways past these transition structures, and contributions from multiple transition structures differing in conformation/configuration. The difficulties associated with modeling each of these contributors are discussed here, along with possible solutions, all with an eye toward the development of portable qualitative models of use to experimentalists aiming to design reactions that make use of entropy to control kinetic selectivity.
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Affiliation(s)
- Dean J Tantillo
- Department of Chemistry, University of California-Davis, 1 Shields Ave, Davis, California 95616, United States
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27
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Mukherjee S, Barbatti M. A Hessian-Free Method to Prevent Zero-Point Energy Leakage in Classical Trajectories. J Chem Theory Comput 2022; 18:4109-4116. [PMID: 35679615 DOI: 10.1021/acs.jctc.2c00216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The problem associated with the zero-point energy (ZPE) leak in classical trajectory calculations is well known. Since ZPE is a manifestation of the quantum uncertainty principle, there are no restrictions on energy during the classical propagation of nuclei. This phenomenon can lead to unphysical results, such as forming products without the ZPE in the internal vibrational degrees of freedom (DOFs). The ZPE leakage also permits reactions below the quantum threshold for the reaction. We have developed a new Hessian-free method, inspired by the Lowe-Andersen thermostat model, to prevent energy dipping below a threshold in the local-pair (LP) vibrational DOFs. The idea is to pump the leaked energy to the corresponding local vibrational mode taken from the other vibrational DOFs. We have applied the new correction protocol on the ab-initio ground-state molecular dynamics simulation of the water dimer (H2O)2, which dissociates due to unphysical ZPE spilling from high-frequency OH modes. The LP-ZPE method has been able to prevent the ZPE spilling of the OH stretching modes by pumping back the leaked energy into the corresponding modes, while this energy is taken from the other modes of the dimer itself, keeping the system as a microcanonical ensemble.
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Affiliation(s)
| | - Mario Barbatti
- Aix Marseille University, CNRS, ICR, Marseille, France.,Institut Universitaire de France, 75231 Paris, France
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28
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Mukherjee S, Pinheiro M, Demoulin B, Barbatti M. Simulations of molecular photodynamics in long timescales. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2022; 380:20200382. [PMID: 35341303 PMCID: PMC8958277 DOI: 10.1098/rsta.2020.0382] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Nonadiabatic dynamics simulations in the long timescale (much longer than 10 ps) are the next challenge in computational photochemistry. This paper delimits the scope of what we expect from methods to run such simulations: they should work in full nuclear dimensionality, be general enough to tackle any type of molecule and not require unrealistic computational resources. We examine the main methodological challenges we should venture to advance the field, including the computational costs of the electronic structure calculations, stability of the integration methods, accuracy of the nonadiabatic dynamics algorithms and software optimization. Based on simulations designed to shed light on each of these issues, we show how machine learning may be a crucial element for long time-scale dynamics, either as a surrogate for electronic structure calculations or aiding the parameterization of model Hamiltonians. We show that conventional methods for integrating classical equations should be adequate to extended simulations up to 1 ns and that surface hopping agrees semiquantitatively with wave packet propagation in the weak-coupling regime. We also describe our optimization of the Newton-X program to reduce computational overheads in data processing and storage. This article is part of the theme issue 'Chemistry without the Born-Oppenheimer approximation'.
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Affiliation(s)
| | - Max Pinheiro
- Aix Marseille University, CNRS, ICR, Marseille, France
| | | | - Mario Barbatti
- Aix Marseille University, CNRS, ICR, Marseille, France
- Institut Universitaire de France, 75231 Paris, France
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29
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Høyer NM, Johnson MS, Mikkelsen KV. Perturbation of the UV transitions of formaldehyde by TiO 2 photocatalysts and Au n nanoclusters. Phys Chem Chem Phys 2022; 24:11395-11411. [PMID: 35503101 DOI: 10.1039/d1cp05820g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the gas phase, formaldehyde has an electric-dipole forbidden transition that becomes allowed by vibronic coupling. In this paper we explore whether perturbation by surfaces could also enhance light absorption by CH2O. We investigate the electronic transitions of formaldehyde in the gas phase and interacting with rutile (110) TiO2, Aun nanoclusters, and Aun on (110)-TiO2. These surfaces are chosen as being representative of metals and metal-oxide minerals, and also because of specific interest in photocatalysts and noble metal nanocluster catalysts. The oscillator strength of the forbidden n → π* transition of formaldehyde in vacuum is investigated by modelling vibrational coupling to the electronic transition with equation-of-motion coupled cluster theory. The excitation energies and oscillator strengths of formaldehyde are calculated for different orientations and distances to the surfaces using the coupled cluster singles and doubles linear response method within the Quantum Mechanical and Molecular Mechanical (QM/MM) model using the aug-cc-pVTZ basis set and compared with the values calculated in vacuo. The electronic transitions of formaldehyde vary very little when placed near a pure TiO2-surface with only minor variations depending on the orientation of formaldehyde. Introducing a gold nanoparticle (by itself or supported by TiO2) induces dramatic changes in the absorption properties. This is due to vibronic interactions and the effect of the broken symmetry on the n → π* transition. We see a large redshift in the transition of 90 nm and oscillator strengths larger than 1.0 × 10-4 for CH2O interacting with Aun.
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Affiliation(s)
- Nicolai Machholdt Høyer
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK 2100 Copenhagen Ø, Denmark.
| | - Matthew S Johnson
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK 2100 Copenhagen Ø, Denmark.
| | - Kurt V Mikkelsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK 2100 Copenhagen Ø, Denmark.
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30
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Kasai T, Muthiah B, Po X, Yan C, Lin K, Tanudji J, Diño WA. Pattern analysis of the impact‐parameter dependent trajectories for the H +
H
2
exchange reaction at
T
=
3
and
300 K
: A characteristic propensity for reactive versus nonreactive trajectories found in the time‐dependent interaction potential and a roaming‐like libration motion at cold temperature. J CHIN CHEM SOC-TAIP 2022. [DOI: 10.1002/jccs.202100539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Toshio Kasai
- Department of Chemistry National Taiwan University Taipei Taiwan
- Department of Applied Physics Osaka University Suita Japan
| | | | - Xin‐Hui Po
- Department of Chemistry National Taiwan University Taipei Taiwan
- Department of Statistics National Chengchi University Taipei Taiwan
| | - Chu‐Chun Yan
- Department of Chemistry National Taiwan University Taipei Taiwan
| | - King‐Chuen Lin
- Department of Chemistry National Taiwan University Taipei Taiwan
- Department of Chemistry, Institute of Atomic and Molecular Sciences Academia Sinica Taipei Taiwan
| | | | - Wilson Agerico Diño
- Department of Applied Physics Osaka University Suita Japan
- Center for Atomic and Molecular Technologies Osaka University Suita Japan
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31
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Meuwly M. Atomistic Simulations for Reactions and Vibrational Spectroscopy in the Era of Machine Learning─ Quo Vadis?. J Phys Chem B 2022; 126:2155-2167. [PMID: 35286087 DOI: 10.1021/acs.jpcb.2c00212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atomistic simulations using accurate energy functions can provide molecular-level insight into functional motions of molecules in the gas and in the condensed phase. This Perspective delineates the present status of the field from the efforts of others and some of our own work and discusses open questions and future prospects. The combination of physics-based long-range representations using multipolar charge distributions and kernel representations for the bonded interactions is shown to provide realistic models for the exploration of the infrared spectroscopy of molecules in solution. For reactions, empirical models connecting dedicated energy functions for the reactant and product states allow statistically meaningful sampling of conformational space whereas machine-learned energy functions are superior in accuracy. The future combination of physics-based models with machine-learning techniques and integration into all-purpose molecular simulation software provides a unique opportunity to bring such dynamics simulations closer to reality.
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Affiliation(s)
- Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
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32
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Chakraborty D, Hase WL. Direct dynamics simulation of the thermal O(
3
P) + dimethylamine reaction in the triplet surface. I. Rate constant and product branching. J PHYS ORG CHEM 2022. [DOI: 10.1002/poc.4339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Debdutta Chakraborty
- Department of Chemistry and Biochemistry Texas Tech University Lubbock Texas USA
- Department of Chemistry Birla Institute of Technology Mesra Ranchi India
| | - William L. Hase
- Department of Chemistry and Biochemistry Texas Tech University Lubbock Texas USA
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33
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Jacob LSD, Lee KLK, Schmidt TW, Nauta K, Kable SH. The dynamics of CO production from the photolysis of acetone across the whole S1 ← S0 absorption spectrum: Roaming and triple fragmentation pathways. J Chem Phys 2022; 156:094303. [DOI: 10.1063/5.0080904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The unimolecular photodissociation dynamics of acetone spanning the entire S1 ← S0 absorption spectrum have been reinvestigated, with a focus on mechanisms that produce CO. At excitation wavelengths of λ > 305.8 nm, all photoproducts are formed on the S0 state after internal conversion. A roaming mechanism forming C2H6 + CO is active in the window λ = 311.2–305.8 nm. From λ = 305.8 to 262 nm, little or no CO is produced with the photochemistry dominated by the Norrish-type I C–C bond cleavage on the lowest excited triplet state, T1. At higher energy ( λ < 262 nm), an increasing fraction of CH3CO radicals from the primary reaction have sufficient internal energy to spontaneously decompose to CH3 + CO. A new model is presented to account for the kinetic energy distribution of the secondary CH3 radical, allowing us to determine the height of the energetic barrier to CH3CO decomposition as 68 ± 4 kJ mol−1, which lies midway between previous measurements. The fraction of CO from triple fragmentation rises smoothly from 260 to 248 nm. We see no evidence of the return of roaming, or any other S0 reaction, in this higher energy region of the first electronic absorption band.
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Affiliation(s)
- L. S. D. Jacob
- School of Chemistry, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - K. L. K. Lee
- School of Chemistry, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - T. W. Schmidt
- School of Chemistry, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - K. Nauta
- School of Chemistry, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - S. H. Kable
- School of Chemistry, University of New South Wales, Kensington, New South Wales 2052, Australia
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34
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Farantos SC. Hamiltonian chemical kinetics for studying roaming in formaldehyde dissociation: Linear and nonlinear models. J PHYS ORG CHEM 2022. [DOI: 10.1002/poc.4334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Stavros C. Farantos
- Department of Chemistry University of Crete Heraklion Greece
- Institute of Electronic Structure and Laser, Foundation for Research and Technology‐Hellas Heraklion Greece
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35
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Mechanistic differences between methanol and dimethyl ether in zeolite-catalyzed hydrocarbon synthesis. Proc Natl Acad Sci U S A 2022; 119:2103840119. [PMID: 35046020 PMCID: PMC8794837 DOI: 10.1073/pnas.2103840119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2021] [Indexed: 11/18/2022] Open
Abstract
Methanol conversion to hydrocarbons has emerged as a key reaction for synthetic energy carriers and light alkenes. The autocatalytic nature and complex reaction network make a mechanistic understanding very challenging and widely debated. Water is not only part of the overall conversion, it is also frequently used as diluent, influencing, in turn, activity, selectivity, and stability of the catalysts. Water directly and indirectly influences the processes that initiate the C–C formation via adjusting the chemical potential of methanol and dimethyl ether, with the latter being more efficient to generate highly reactive C1 species via hydride transfer. The insight shows paths to optimize the stability of catalysts and to tailor the product distribution for H-ZSM-5–based catalysts. Water influences critically the kinetics of the autocatalytic conversion of methanol to hydrocarbons in acid zeolites. At very low conversions but otherwise typical reaction conditions, the initiation of the reaction is delayed in presence of H2O. In absence of hydrocarbons, the main reactions are the methanol and dimethyl ether (DME) interconversion and the formation of a C1 reactive mixture—which in turn initiates the formation of first hydrocarbons in the zeolite pores. We conclude that the dominant reactions for the formation of a reactive C1 pool at this stage involve hydrogen transfer from both MeOH and DME to surface methoxy groups, leading to methane and formaldehyde in a 1:1 stoichiometry. While formaldehyde reacts further to other C1 intermediates and initiates the formation of first C–C bonds, CH4 is not reacting. The hydride transfer to methoxy groups is the rate-determining step in the initiation of the conversion of methanol and DME to hydrocarbons. Thus, CH4 formation rates at very low conversions, i.e., in the initiation stage before autocatalysis starts, are used to gauge the formation rates of first hydrocarbons. Kinetics, in good agreement with theoretical calculations, show surprisingly that hydrogen transfer from DME to methoxy species is 10 times faster than hydrogen transfer from methanol. This difference in reactivity causes the observed faster formation of hydrocarbons in dry feeds, when the concentration of methanol is lower than in presence of water. Importantly, the kinetic analysis of CH4 formation rates provides a unique quantitative parameter to characterize the activity of catalysts in the methanol-to-hydrocarbon process.
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36
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Endo T, Neville SP, Lassonde P, Qu C, Fujise H, Fushitani M, Hishikawa A, Houston PL, Bowman JM, Légaré F, Schuurman MS, Ibrahim H. Electronic relaxation and dissociation dynamics in formaldehyde: pump wavelength dependence. Phys Chem Chem Phys 2022; 24:1779-1786. [PMID: 34985091 DOI: 10.1039/d1cp04264e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The effect of the incident UV pump wavelength on the subsequent excited state dynamics, electronic relaxation, and ultimate dissociation of formaldehyde is studied using first principles simulation and Coulomb explosion imaging (CEI) experiments. Transitions in a vibronic progression in the à ← X̃ absorption band are systematically prepared using a tunable UV source which generates pulses centered at 304, 314, 329, and 337 nm. We find, both via ab initio simulation and experimental results, that the rate of excited state decay and subsequent dissociation displays a prominent dependence on which vibronic transition in the absorption band is prepared by the pump. Our simulations predict that nonadiabatic transition rates and dissociation yields will increase by a factor of >100 as the pump wavelength is decreased from 337 to 304 nm. The experimental results and theoretical simulations are in broad agreement and both indicate that the dissociation rate plateaus rapidly after ≈2 ps following an ultrafast sub-ps rise.
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Affiliation(s)
- Tomoyuki Endo
- Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, QC J3X 1S2, Canada. .,Kansai Photon Science Institute, National Institutes for Quantum Science and Technology, Umemidai, Kizugawa, Kyoto 619-0215, Japan.
| | - Simon P Neville
- National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
| | - Philippe Lassonde
- Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, QC J3X 1S2, Canada.
| | - Chen Qu
- Department of Chemistry & Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - Hikaru Fujise
- Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Mizuho Fushitani
- Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Akiyoshi Hishikawa
- Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan.,Research Center for Materials Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Paul L Houston
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14852, USA.,School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Joel M Bowman
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| | - François Légaré
- Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, QC J3X 1S2, Canada.
| | - Michael S Schuurman
- National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada.,Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, ON K1N 6N5, Canada.
| | - Heide Ibrahim
- Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, QC J3X 1S2, Canada.
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37
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Green WH. Concluding Remarks on Faraday Discussion on Unimolecular Reactions. Faraday Discuss 2022; 238:741-766. [DOI: 10.1039/d2fd00136e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This Faraday Discussion, marking the centenary of Lindemann’s explanation of the pressure-dependence of unimolecular reactions, presented recent advances in measuring and computing collisional energy transfer efficiencies, microcanonical rate coefficients, pressure-dependent...
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38
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Bhattacharyya S, Borne K, Ziaee F, Pathak S, Wang E, Venkatachalam AS, Marshall N, Carnes KD, Fehrenbach CW, Severt T, Ben-Itzhak I, Rudenko A, Rolles D. Two- and three-body fragmentation of multiply charged tribromomethane by ultrafast laser pulses. Phys Chem Chem Phys 2022; 24:27631-27644. [DOI: 10.1039/d2cp03089f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
This article provides mechanistic insight into the two- and three-body fragmentation dynamics of CHBr3 after strong-field ionization and discusses the possible isomerization of CHBr3 to BrCHBr–Br (iso-CHBr3) prior to the fragmentation.
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Affiliation(s)
- Surjendu Bhattacharyya
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Kurtis Borne
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Farzaneh Ziaee
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Shashank Pathak
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Enliang Wang
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Anbu Selvam Venkatachalam
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Nathan Marshall
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Kevin D. Carnes
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Charles W. Fehrenbach
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Travis Severt
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Itzik Ben-Itzhak
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Artem Rudenko
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
| | - Daniel Rolles
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506, USA
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39
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Yadav K, Pradhan R, Lourderaj U. Influence of second-order saddles on reaction mechanisms. Faraday Discuss 2022; 238:183-203. [DOI: 10.1039/d2fd00026a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The transition state, a first-order saddle point on the potential energy surface, plays a central role in understanding the mechanism, dynamics, and rate of chemical reactions. However, we recently identified...
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40
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Fang YG, Fang WH. Excited-State Dependent Hydrogen Bond Natures and Their Critical Role in Determining the Photophysical Properties of Aromatic Thioketones. Phys Chem Chem Phys 2022; 24:17059-17067. [DOI: 10.1039/d2cp02016e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, how the excited-state dependent hydrogen bond (H-bond) interactions control photophysical processes have been uncovered by accurate electronic structure calculations for the five lowest-lying states (S0, S1, S2,...
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41
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Roaming dynamics of the H+C 2D 2 reaction on a fundamental-invariant neural network potential energy surface. CHINESE J CHEM PHYS 2022. [DOI: 10.1063/1674-0068/cjcp2111249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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42
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Foley CD, Xie C, Guo H, Suits A. Quantum resonances and roaming dynamics in formaldehyde photodissociation. Faraday Discuss 2022; 238:249-265. [DOI: 10.1039/d2fd00050d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The unimolecular dissociation of formaldehyde is studied via excitation to the à band at several excitation energies from just below the ground state radical dissociation threshold to 5000 cm-1 above...
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43
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Choi EH, Lee Y, Heo J, Ihee H. Reaction dynamics studied via femtosecond X-ray liquidography at X-ray free-electron lasers. Chem Sci 2022; 13:8457-8490. [PMID: 35974755 PMCID: PMC9337737 DOI: 10.1039/d2sc00502f] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 06/06/2022] [Indexed: 02/04/2023] Open
Abstract
X-ray free-electron lasers (XFELs) provide femtosecond X-ray pulses suitable for pump–probe time-resolved studies with a femtosecond time resolution. Since the advent of the first XFEL in 2009, recent years have witnessed a great number of applications with various pump–probe techniques at XFELs. Among these, time-resolved X-ray liquidography (TRXL) is a powerful method for visualizing structural dynamics in the liquid solution phase. Here, we classify various chemical and biological molecular systems studied via femtosecond TRXL (fs-TRXL) at XFELs, depending on the focus of the studied process, into (i) bond cleavage and formation, (ii) charge distribution and electron transfer, (iii) orientational dynamics, (iv) solvation dynamics, (v) coherent nuclear wavepacket dynamics, and (vi) protein structural dynamics, and provide a brief review on each category. We also lay out a plausible roadmap for future fs-TRXL studies for areas that have not been explored yet. Femtosecond X-ray liquidography using X-ray free-electron lasers (XFELs) visualizes various aspects of reaction dynamics.![]()
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Affiliation(s)
- Eun Hyuk Choi
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
| | - Yunbeom Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
| | - Jun Heo
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
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44
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Lin S, Peng D, Yang W, Gu FL, Lan Z. Theoretical studies on triplet-state driven dissociation of formaldehyde by quasi-classical molecular dynamics simulation on machine-learning potential energy surface. J Chem Phys 2021; 155:214105. [PMID: 34879677 PMCID: PMC8654486 DOI: 10.1063/5.0067176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 11/09/2021] [Indexed: 11/15/2022] Open
Abstract
The H-atom dissociation of formaldehyde on the lowest triplet state (T1) is studied by quasi-classical molecular dynamic simulations on the high-dimensional machine-learning potential energy surface (PES) model. An atomic-energy based deep-learning neural network (NN) is used to represent the PES function, and the weighted atom-centered symmetry functions are employed as inputs of the NN model to satisfy the translational, rotational, and permutational symmetries, and to capture the geometry features of each atom and its individual chemical environment. Several standard technical tricks are used in the construction of NN-PES, which includes the application of clustering algorithm in the formation of the training dataset, the examination of the reliability of the NN-PES model by different fitted NN models, and the detection of the out-of-confidence region by the confidence interval of the training dataset. The accuracy of the full-dimensional NN-PES model is examined by two benchmark calculations with respect to ab initio data. Both the NN and electronic-structure calculations give a similar H-atom dissociation reaction pathway on the T1 state in the intrinsic reaction coordinate analysis. The small-scaled trial dynamics simulations based on NN-PES and ab initio PES give highly consistent results. After confirming the accuracy of the NN-PES, a large number of trajectories are calculated in the quasi-classical dynamics, which allows us to get a better understanding of the T1-driven H-atom dissociation dynamics efficiently. Particularly, the dynamics simulations from different initial conditions can be easily simulated with a rather low computational cost. The influence of the mode-specific vibrational excitations on the H-atom dissociation dynamics driven by the T1 state is explored. The results show that the vibrational excitations on symmetric C-H stretching, asymmetric C-H stretching, and C=O stretching motions always enhance the H-atom dissociation probability obviously.
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Affiliation(s)
| | | | - Weitao Yang
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Feng Long Gu
- Authors to whom correspondence should be addressed: and
| | - Zhenggang Lan
- Authors to whom correspondence should be addressed: and
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Foley CD, Xie C, Guo H, Suits AG. Orbiting resonances in formaldehyde reveal coupling of roaming, radical, and molecular channels. Science 2021; 374:1122-1127. [PMID: 34822294 DOI: 10.1126/science.abk0634] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Casey D Foley
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA
| | - Changjian Xie
- Institute of Modern Physics, Shaanxi Key Laboratory for Theoretical Physics Frontiers, Northwest University, Xian, Shaanxi 710127, China.,Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA
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46
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Ramasesha K, Savee JD, Zádor J, Osborn DL. A New Pathway for Intersystem Crossing: Unexpected Products in the O( 3P) + Cyclopentene Reaction. J Phys Chem A 2021; 125:9785-9801. [PMID: 34730957 DOI: 10.1021/acs.jpca.1c05817] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We investigated the reaction of O(3P) with cyclopentene at 4 Torr and 298 K using time-resolved multiplexed photoionization mass spectrometry, where O(3P) radicals were generated by 351 nm photolysis of NO2 and reacted with excess cyclopentene in He under pseudo-first-order conditions. The resulting products were sampled, ionized, and detected by tunable synchrotron vacuum ultraviolet radiation and an orthogonal acceleration time-of-flight mass spectrometer. This technique enabled measurement of both mass spectra and photoionization spectra as functions of time following the initiation of the reaction. We observe propylketene (41%), acrolein + ethene (37%), 1-butene + CO (19%), and cyclopentene oxide (3%), of which the propylketene pathway was previously unidentified experimentally and theoretically. The automatically explored reactive potential energy landscape at the CCSD(T)-F12a/cc-pVTZ//ωB97X-D/6-311++G(d,p) level and the related master equation calculations predict that cyclopentene oxide is formed on the singlet potential energy surface, whereas propylketene is first formed on the triplet surface. These calculations provide evidence that significant intersystem crossing can happen in this reaction not only around the geometry of the initial triplet adduct but also around that of triplet propylketene. The formation of 1-butene + CO is initiated on the triplet surface, with bond cleavage and hydrogen transfer occurring during intersystem crossing to the singlet surface. At present, we are unable to explain the mechanistic origins of the acrolein + ethene channel, and we thus refrain from assigning singlet or triplet reactivity to this channel. Overall, at least 60% of the products result from triplet reactivity. We propose that the reactivity of cyclic alkenes with O(3P) is influenced by their greater effective degree of unsaturation compared with acyclic alkenes. This work also suggests that searches for minimum-energy crossing points that connect triplet surfaces to singlet surfaces should extend beyond the initial adducts.
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Affiliation(s)
- Krupa Ramasesha
- Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969, United States
| | - John D Savee
- Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969, United States
| | - Judit Zádor
- Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969, United States
| | - David L Osborn
- Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969, United States.,Department of Chemical Engineering, University of California, Davis, California 95616, United States
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Guan Y, Xie C, Yarkony DR, Guo H. High-fidelity first principles nonadiabaticity: diabatization, analytic representation of global diabatic potential energy matrices, and quantum dynamics. Phys Chem Chem Phys 2021; 23:24962-24983. [PMID: 34473156 DOI: 10.1039/d1cp03008f] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Nonadiabatic dynamics, which goes beyond the Born-Oppenheimer approximation, has increasingly been shown to play an important role in chemical processes, particularly those involving electronically excited states. Understanding multistate dynamics requires rigorous quantum characterization of both electronic and nuclear motion. However, such first principles treatments of multi-dimensional systems have so far been rather limited due to the lack of accurate coupled potential energy surfaces and difficulties associated with quantum dynamics. In this Perspective, we review recent advances in developing high-fidelity analytical diabatic potential energy matrices for quantum dynamical investigations of polyatomic uni- and bi-molecular nonadiabatic processes, by machine learning of high-level ab initio data. Special attention is paid to methods of diabatization, high fidelity construction of multi-state coupled potential energy surfaces and property surfaces, as well as quantum mechanical characterization of nonadiabatic nuclear dynamics. To illustrate the tremendous progress made by these new developments, several examples are discussed, in which direct comparison with quantum state resolved measurements led to either confirmation of the observation or sometimes reinterpretation of the experimental data. The insights gained in these prototypical systems greatly advance our understanding of nonadiabatic dynamics in chemical systems.
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Affiliation(s)
- Yafu Guan
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
| | - Changjian Xie
- Institute of Modern Physics, Northwest University, Xi'an, Shaanxi 710069, China.
| | - David R Yarkony
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, 87131, USA.
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48
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Xie C, Guan Y, Yarkony DR, Guo H. Vibrational energy levels of the S0 and S1 states of formaldehyde using an accurate ab initio based global diabatic potential energy matrix. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1918775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Changjian Xie
- Institute of Modern Physics, Northwest University, Xi’an, Shaanxi, People’s Republic of China
| | - Yafu Guan
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - David R. Yarkony
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, USA
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Chernicharo FCS, Modesto-Costa L, Borges I. Simulation of the electron ionization mass spectra of the Novichok nerve agent. JOURNAL OF MASS SPECTROMETRY : JMS 2021; 56:e4779. [PMID: 34407561 DOI: 10.1002/jms.4779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
Novichok is one of the most feared and controversial nerve agents, which existence was confirmed only after the Salisbury attack in 2018. A new attack on August 2020, in Russia, was confirmed. After the 2018 attack, the agent was included in the list of the most dangerous chemicals of the Chemical Weapons Convention (CWC). However, information related to its electron ionization mass spectrometry (EI/MS), essential for unambiguous identification, is scarce. Therefore, investigations about Novichok EI/MS are urgent. In this work, we employed Born-Oppenheimer molecular dynamics through the Quantum Chemistry Electron Ionization Mass Spectrometry (QCEIMS) method to simulate and rationalize the EI/MS spectra and fragmentation pathways of 32 Novichok molecules recently incorporated into the CWC. The comparison of additional simulations with the measured EI spectrum of another Novichok analog is very favorable. A general scheme of the fragmentation pathways derived from simulation results was presented. The present results will be useful for elucidation and prediction of the EI spectra and fragmentation pathways of the dangerous Novichok nerve agent.
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Affiliation(s)
| | - Lucas Modesto-Costa
- Departamento de Química, Instituto Militar de Engenharia, Rio de Janeiro, RJ, Brazil
| | - Itamar Borges
- Departamento de Química, Instituto Militar de Engenharia, Rio de Janeiro, RJ, Brazil
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Datta S, Davis HF. Dimethylcarbene versus Direct Propene Formation in Dimethylketene Photodissociation. J Phys Chem A 2021; 125:6940-6948. [PMID: 34369788 DOI: 10.1021/acs.jpca.1c03641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Highly reactive carbenes are usually produced by photolysis of ketenes, diazoalkanes, or diazirines. Sequential kinetic pathways for deactivation of nascent carbenes usually involve bimolecular reactions in competition with isomerization producing stable products such as alkenes. However, the direct photolytic production of stable products, effectively bypassing formation of free carbenes, has been postulated for over 50 years but remains very poorly understood. Often termed "rearrangement in the excited state" (RIES), examples include 1,2-hydrogen migration within photoexcited carbene precursors yielding alkenes and the Wolff rearrangement in photogenerated carbonyl-substituted carbenes producing ketenes. In this study, the two competing CO elimination channels from photoexcited gaseous dimethylketene, producing dimethylcarbene and propene, were studied as a function of electronic excitation energy, under collision-free conditions, by using photofragment translational energy spectroscopy with vacuum ultraviolet photoionization of the products. A significant fraction of the dimethylcarbene → propene isomerization exothermicity (∼300 kJ/mol) was released as propene + CO translational energy, indicating that propene is formed prior to or concurrent with CO elimination. An increase in the propene yield with increasing excitation energy suggests that the effective potential energy barrier for this channel lies ∼24 kJ/mol above the energetic threshold for dimethylcarbene formation via C═C bond fission. Possible mechanisms for direct propene elimination are discussed in light of the observed energy dependence for the competing pathways.
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Affiliation(s)
- Sagnik Datta
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, United States
| | - H Floyd Davis
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, United States
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