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Garcia JM, Sayres SG. Tuning the photodynamics of sub-nanometer neutral chromium oxide clusters through sequential oxidation. NANOSCALE 2022; 14:7798-7806. [PMID: 35535667 DOI: 10.1039/d2nr00464j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Sub-nanometer neutral chromium oxide clusters were produced in the gas phase through laser ablation and their low-lying excited state lifetimes were measured using femtosecond pump-probe spectroscopy. Time-dependent density functional theory calculations relate the trends in experimental lifetimes to the cluster's electronic structure. The photoexcited (CrO2)n (n < 5) cluster transients with the absence of up to four O atoms (CrnO2n-x, x < 5) exhibit a ∼30 fs and sub-ps lifetime, attributed to instantaneous metallic e-e scattering and vibrationally mediated charge carrier relaxation, respectively. A long-lived (>2 ps) response is found in both small and clusters with low O content, indicating that terminal CrO bonds facilitate efficient excited state relaxation. The ∼30 fs transient signal fraction grows nearly linearly with oxidation, matching the amount of O-2p to Cr-3d charge transfer character of the photoexcitation and suggesting a gradual transition between semiconducting and metallic behavior in chromium oxide clusters at the molecular level. The results presented herein suggest that the photocatalytic properties of chromium oxides can be tunable based on size and oxidation.
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Affiliation(s)
- Jacob M Garcia
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.
- Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, AZ 85287, USA
| | - Scott G Sayres
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.
- Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, AZ 85287, USA
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Garcia JM, Heald LF, Shaffer RE, Sayres SG. Effect of oxidation on excited state dynamics of neutral Ti nO 2n-x (n < 10, x < 4) clusters. J Chem Phys 2021; 155:211102. [PMID: 34879680 DOI: 10.1063/5.0071264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Excited state lifetimes of neutral titanium oxide clusters (TinO2n-x, n < 10, x < 4) were measured using a sequence of 400 nm pump and 800 nm probe femtosecond laser pulses. Despite large differences in electronic properties between the closed shell stoichiometric TinO2n clusters and the suboxide TinO2n-x (x = 1-3) clusters, the transient responses for all clusters contain a fast response of 35 fs followed by a sub-picosecond (ps) excited state lifetime. In this non-scalable size regime, subtle changes in the sub-ps lifetimes are attributed to variations in the coordination of Ti atoms and localization of charge carriers following UV photoexcitation. In general, clusters exhibit longer lifetimes with increased size and also with the addition of O atoms. This suggests that the removal of O atoms develops stronger Ti-Ti interactions as the system transitions from a semiconducting character to a fast metallic electronic relaxation mechanism.
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Affiliation(s)
- Jacob M Garcia
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Lauren F Heald
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Ryan E Shaffer
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Scott G Sayres
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
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Garcia JM, Sayres SG. Increased Excited State Metallicity in Neutral Cr 2O n Clusters ( n < 5) upon Sequential Oxidation. J Am Chem Soc 2021; 143:15572-15575. [PMID: 34516101 DOI: 10.1021/jacs.1c07275] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Excited state lifetimes of neutral Cr2On (n < 5) clusters were measured using femtosecond pump-probe spectroscopy. Density functional theory calculations reveal that the excited state dynamics are correlated with changes in the cluster's electronic structure with increasing oxidation. Upon absorption of a UV (400 nm) photon, the clusters exhibit features attributed to three separate relaxation processes. All clusters exhibit similar subpicosecond lifetimes, attributed to vibrational relaxation. However, the ∼30 fs transient signal fraction grows linearly with oxidation, matching the amount of O to Cr charge transfer character of the photoexcitation and highlighting a gradual transition between semiconducting and metallic behavior at the molecular level. A long-lived (>2.5 ps) response is recorded only in clusters with significant d-electron character, suggesting that adiabatic relaxation back to the ground state is efficient in heavily oxidized clusters, due to the presence of terminal O atoms. The simple picture of sequential oxidation of Cr2On reveals a linear variation in the contributions of each relaxation component to the total transient signals, therefore opening possibilities for the design of new molecular spintronic materials.
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Affiliation(s)
- Jacob M Garcia
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States.,Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, Arizona 85287, United States
| | - Scott G Sayres
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States.,Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, Arizona 85287, United States
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Topolski JE, Kafader JO, Marrero-Colon V, Iyengar SS, Hratchian HP, Jarrold CC. Exotic electronic structures of SmxCe3−xOy (x = 0-3; y = 2-4) clusters and the effect of high neutral density of low-lying states on photodetachment transition intensities. J Chem Phys 2018; 149:054305. [DOI: 10.1063/1.5043490] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Josey E. Topolski
- Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, Indiana 47405, USA
| | - Jared O. Kafader
- Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, Indiana 47405, USA
| | - Vicmarie Marrero-Colon
- Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, Indiana 47405, USA
| | - Srinivasan S. Iyengar
- Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, Indiana 47405, USA
| | - Hrant P. Hratchian
- Department of Chemistry and Chemical Biology, University of California, Merced, 5200 North Lake Road, Merced, California 95343, USA
| | - Caroline Chick Jarrold
- Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, Indiana 47405, USA
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Hansen K, Richter R, Alagia M, Stranges S, Schio L, Salén P, Yatsyna V, Feifel R, Zhaunerchyk V. Single Photon Thermal Ionization of C_{60}. PHYSICAL REVIEW LETTERS 2017; 118:103001. [PMID: 28339240 DOI: 10.1103/physrevlett.118.103001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Indexed: 06/06/2023]
Abstract
We report on experiments which show that C_{60} can ionize in an indirect, quasithermal boiloff process after absorption of a single photon. The process involves a large number of incoherently excited valence electrons and yields electron spectra with a Boltzmann distribution with temperatures exceeding 10^{4} K. It is expected to be present for other molecules and clusters with a comparatively large number of valence electrons. The astrophysical consequences are briefly discussed.
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Affiliation(s)
- Klavs Hansen
- Tianjin International Center of Nanoparticles and Nanosystems, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
| | - Robert Richter
- Elettra-Sincrotrone Trieste, Area Science Park, 34149 Basovizza, Trieste, Italy
| | - Michele Alagia
- IOM-CNR Tasc, SS-14, Km 163.5 Area Science Park, Basovizza 34149, Trieste, Italy
| | - Stefano Stranges
- IOM-CNR Tasc, SS-14, Km 163.5 Area Science Park, Basovizza 34149, Trieste, Italy
- Dipartimento di Chimica e Tecnologie del Farmaco, Universitá Sapienza, Rome I-00185, Italy
| | - Luca Schio
- IOM-CNR Tasc, SS-14, Km 163.5 Area Science Park, Basovizza 34149, Trieste, Italy
| | - Peter Salén
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - Vasyl Yatsyna
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
| | - Raimund Feifel
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
| | - Vitali Zhaunerchyk
- Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden
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Hansen K. Single photon transient hot electron ionization of C 60. Phys Chem Chem Phys 2017; 19:19699-19706. [DOI: 10.1039/c7cp01705g] [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
Survival probability vs. time of hot electron-excited C60 at energies 10 through 70 eV.
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Affiliation(s)
- K. Hansen
- Tianjin International Center of Nanoparticles and Nanosystems
- Tianjin University
- Tianjin 300072
- P. R. China
- Department of Physics
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Braun C, Proch S, Kim YD, Ganteför G. Relaxation dynamics of the mass-selected hydrated Auride ion (Au−). Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.09.064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Studies of femtosecond time-resolved photoelectron spectroscopy of Au3-(H2O)m clusters: Alteration of cluster relaxation dynamics of metal clusters by water molecules. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.01.078] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Verlet JRR. Femtosecond spectroscopy of cluster anions: insights into condensed-phase phenomena from the gas-phase. Chem Soc Rev 2007; 37:505-17. [PMID: 18224260 DOI: 10.1039/b700528h] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ultrafast spectroscopy allows chemical and physical processes to be observed on time-scales faster than the nuclear motion within molecules. This tutorial review explores how such experiments, and specifically time-resolved photoelectron spectroscopy on gas-phase cluster anions, provide a molecular-level understanding of the processes that are normally associated with condensed-phase dynamics.
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Affiliation(s)
- Jan R R Verlet
- Department of Chemistry, University of Durham, Durham, UK.
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Bragg AE, Verlet JRR, Kammrath A, Cheshnovsky O, Neumark DM. Time-resolved intraband electronic relaxation dynamics of Hgn− clusters (n=7–13,15,18) excited at 1.0 eV. J Chem Phys 2005; 122:54314. [PMID: 15740329 DOI: 10.1063/1.1828042] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Time-resolved photoelectron imaging has been used to study the relaxation dynamics of small Hg(n) (-) clusters (n=7-13,15,18) following intraband electronic excitation at 1250 nm (1.0 eV). This study furthers our previous investigation of single electron, intraband relaxation dynamics in Hg(n) (-) clusters at 790 nm by exploring the dynamics of smaller clusters (n=7-10), as well as those of larger clusters (n=11-13,15,18) at a lower excitation energy. We measure relaxation time scales of 2-9 ps, two to three times faster than seen previously after 790 nm excitation of Hg(n) (-), n=11-18. These results, along with size-dependent trends in the absorption cross-section and photoelectron angular distribution anisotropy, suggest significant evolution of the cluster anion electronic structure in the size range studied here. Furthermore, the smallest clusters studied here exhibit 35-45 cm(-1) oscillations in pump-probe signal at earliest temporal delays that are interpreted as early coherent nuclear motion on the excited potential energy surfaces of these clusters. Evidence for evaporation of one or two Hg atoms is seen on a time scale of tens of picoseconds.
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Affiliation(s)
- Arthur E Bragg
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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Verlet JRR, Bragg AE, Kammrath A, Cheshnovsky O, Neumark DM. Time-resolved relaxation dynamics of Hgn− (11⩽n⩽16,n=18) clusters following intraband excitation at 1.5 eV. J Chem Phys 2004; 121:10015-25. [PMID: 15549877 DOI: 10.1063/1.1809573] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Electron-nuclear relaxation dynamics are studied in Hg(n) (-) (11 <or= n <or= 16,n = 18) using time-resolved photoelectron imaging. The excess electron in the anion uniquely occupies the p band and is excited intraband by 1.53 eV pump photons; the subsequent dynamics are monitored by photodetachment at 3.06 eV and measurement of the photoelectron images as a function of pump-probe delay. The initially excited state decays on a time scale of approximately 10 ps, and subsequent relaxation dynamics reveal a smooth evolution of the photoelectron spectra towards lower electron kinetic energy over 50-100 ps. Qualitatively, the relaxation process is captured by a simple kinetic model assuming a series of radiationless transitions within a dense manifold of electronic states. All the clusters studied show similar dynamics with the exception of Hg(11) (-) in which the initially prepared state does not decay as quickly as the others.
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Affiliation(s)
- Jan R R Verlet
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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Affiliation(s)
- Albert Stolow
- Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 Canada.
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Bauer C, Abid JP, Fermin D, Girault HH. Ultrafast chemical interface scattering as an additional decay channel for nascent nonthermal electrons in small metal nanoparticles. J Chem Phys 2004; 120:9302-15. [PMID: 15267867 DOI: 10.1063/1.1710856] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The use of 4.2 nm gold nanoparticles wrapped in an adsorbates shell and embedded in a TiO2 metal oxide matrix gives the opportunity to investigate ultrafast electron-electron scattering dynamics in combination with electronic surface phenomena via the surface plasmon lifetimes. These gold nanoparticles (NPs) exhibit a large nonclassical broadening of the surface plasmon band, which is attributed to a chemical interface damping. The acceleration of the loss of surface plasmon phase coherence indicates that the energy and the momentum of the collective electrons can be dissipated into electronic affinity levels of adsorbates. As a result of the preparation process, gold NPs are wrapped in a shell of sulfate compounds that gives rise to a large density of interfacial molecules confined between Au and TiO2, as revealed by Fourier-transform-infrared spectroscopy. A detailed analysis of the transient absorption spectra obtained by broadband femtosecond transient absorption spectroscopy allows separating electron-electron and electron-phonon interaction. Internal thermalization times (electron-electron scattering) are determined by probing the decay of nascent nonthermal electrons (NNEs) and the build-up of the Fermi-Dirac electron distribution, giving time constants of 540 to 760 fs at 0.42 and 0.34 eV from the Fermi level, respectively. Comparison with literature data reveals that lifetimes of NNEs measured for these small gold NPs are more than four times longer than for silver NPs with similar sizes. The surprisingly long internal thermalization time is attributed to an additional decay mechanism (besides the classical e-e scattering) for the energy loss of NNEs, identified as the ultrafast chemical interface scattering process. NNEs experience an inelastic resonant scattering process into unoccupied electronic states of adsorbates, that directly act as an efficient heat bath, via the excitation of molecular vibrational modes. The two-temperature model is no longer valid for this system because of (i) the temporal overlap between the internal and external thermalization process is very important; (ii) a part of the photonic energy is directly transferred toward the adsorbates (not among "cold" conduction band electrons). These findings have important consequence for femtochemistry on metal surfaces since they show that reactions can be initiated by nascent nonthermal electrons (as photoexcited, out of a Fermi-Dirac distribution) besides of the hot electron gas.
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Affiliation(s)
- Christophe Bauer
- Laboratoire d'Electrochimie Physique et Analytique, Institut de Chimie Moléculaire et Biologique, Faculté des Sciences de Base, Ecole Polytechnique Fédérale de Lausanne, Switzerland.
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Affiliation(s)
- T E Dermota
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Hou JG, Wang B, Yang J, Wang K, Lu W, Li Z, Wang H, Chen DM, Zhu Q. Disorder and suppression of quantum confinement effects in Pd nanoparticles. PHYSICAL REVIEW LETTERS 2003; 90:246803. [PMID: 12857212 DOI: 10.1103/physrevlett.90.246803] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2002] [Indexed: 05/24/2023]
Abstract
Size-selectable ligand-passivated crystalline and amorphous Pd nanoparticles (<4 nm) are synthesized by a novel two-phase process and verified by high-resolution transmission electron microscopy. Scanning tunneling spectroscopy preformed at 5 K on these two types of nanoparticles exhibits clear Coulomb blockade and Coulomb staircases. Size dependent multipeak spectral features in the differential conductance curve are observed for the crystalline Pd particles but not for the amorphous particles. Theoretical analysis shows that these spectral features are related to the quantized electronic states in the crystalline Pd particle. The suppression of the quantum confinement effect in the amorphous particle arises from the reduction of the degeneracy of the eigenstates and the level broadening due to the reduced lifetime of the electronic states.
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Affiliation(s)
- J G Hou
- Structure Research Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
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Lüttgens G, Pontius N, Bechthold PS, Neeb M, Eberhardt W. Photon-induced thermal desorption of CO from small metal-carbonyl clusters. PHYSICAL REVIEW LETTERS 2002; 88:076102. [PMID: 11863916 DOI: 10.1103/physrevlett.88.076102] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2001] [Indexed: 05/23/2023]
Abstract
Thermal CO desorption from photoexcited free metal-carbonyl clusters has been resolved in real time using two-color pump-probe photoelectron spectroscopy. Sequential energy dissipation steps between the initial photoexcitation and the final desorption event, e.g., electron relaxation and thermalization, have been resolved for Au2(CO)(-) and Pt2(CO)5-. The desorption rates for the two clusters differ considerably due to the different numbers of vibrational degrees of freedom. The unimolecular CO-desorption thresholds of Au2(CO)(-) and Pt2(CO)5- have been approximated by means of a statistical Rice-Ramsperger-Kassel calculation using the experimentally derived desorption rate constants.
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Affiliation(s)
- G Lüttgens
- Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
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