1
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Kranabetter L, Kristensen HH, Ghazaryan A, Schouder CA, Chatterley AS, Janssen P, Jensen F, Zillich RE, Lemeshko M, Stapelfeldt H. Nonadiabatic Laser-Induced Alignment Dynamics of Molecules on a Surface. PHYSICAL REVIEW LETTERS 2023; 131:053201. [PMID: 37595218 DOI: 10.1103/physrevlett.131.053201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 07/08/2023] [Indexed: 08/20/2023]
Abstract
We demonstrate that a sodium dimer, Na_{2}(1^{3}Σ_{u}^{+}), residing on the surface of a helium nanodroplet, can be set into rotation by a nonresonant 1.0 ps infrared laser pulse. The time-dependent degree of alignment measured, exhibits a periodic, gradually decreasing structure that deviates qualitatively from that expected for gas-phase dimers. Comparison to alignment dynamics calculated from the time-dependent rotational Schrödinger equation shows that the deviation is due to the alignment dependent interaction between the dimer and the droplet surface. This interaction confines the dimer to the tangential plane of the droplet surface at the point where it resides and is the reason that the observed alignment dynamics is also well described by a 2D quantum rotor model.
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Affiliation(s)
- Lorenz Kranabetter
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Henrik H Kristensen
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Areg Ghazaryan
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Constant A Schouder
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
- Université Paris-Saclay, CEA, CNRS, LIDYL, 91191 Gif-sur-Yvette, France
| | - Adam S Chatterley
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Paul Janssen
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Frank Jensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Robert E Zillich
- Institute for Theoretical Physics, Johannes Kepler Universität Linz, Altenbergerstraße 69, A-4040 Linz, Austria
| | - Mikhail Lemeshko
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Henrik Stapelfeldt
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
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2
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Saidi S, Mabrouk N, Dhiflaoui J, Berriche H. Structural, Spectroscopic, and Dynamic Properties of Li2+(X2∑g+) in Interaction with Krypton Atom. Molecules 2023; 28:5512. [PMID: 37513385 PMCID: PMC10385072 DOI: 10.3390/molecules28145512] [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: 05/23/2023] [Revised: 07/10/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
We report a computational study of the potential energy surface (PES) and vibrational bound states for the ground electronic state of Li2+Kr. The PES was calculated in Jacobi coordinates at the Restricted Coupled Cluster method RCCSD(T) level of calculation and using aug-cc-pVnZ (n = 4 and 5) basis sets. Afterward, this PES is extrapolated to the complete basis set (CBS) limit for correction. The obtained interaction energies were, then, interpolated numerically using the reproducing kernel Hilbert space polynomial (RKHS) approach to produce analytic expressions for the 2D-PES. The analytical PES is used to solve the nuclear Schrodinger equation to determine the bound states' eigenvalues of Li2+Kr for a J = 0 total angular momentum configuration and to understand the effects of orientational anisotropy of the forces and the interplay between the repulsive and attractive interaction within the potential surface. In addition, the radial and angular distributions of some selected bound state levels, which lie below, around, and above the T-shaped 90° barrier well, are calculated and discussed. We note that the radial distributions clearly acquire a more complicated nodal structure and correspond to bending and stretching vibrational motions "mode" of the Kr atom along the radial coordinate, and the situation becomes very different at the highest bound states levels with energies higher than the T-shaped 90° barrier well. The shape of the distributions becomes even more complicated, with extended angular distributions and prominent differences between even and odd states.
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Affiliation(s)
- Samah Saidi
- Laboratory of Interfaces and Advanced Materials, Physics Department, Faculty of Sciences of Monastir, Avenue de l'Environnement, Monastir 5019, Tunisia
- Department of Physics, College of Science and Humanities in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
| | - Nesrine Mabrouk
- Laboratory of Interfaces and Advanced Materials, Physics Department, Faculty of Sciences of Monastir, Avenue de l'Environnement, Monastir 5019, Tunisia
| | - Jamila Dhiflaoui
- Laboratory of Interfaces and Advanced Materials, Physics Department, Faculty of Sciences of Monastir, Avenue de l'Environnement, Monastir 5019, Tunisia
| | - Hamid Berriche
- Laboratory of Interfaces and Advanced Materials, Physics Department, Faculty of Sciences of Monastir, Avenue de l'Environnement, Monastir 5019, Tunisia
- Mathematics and Natural Sciences Department, School of Arts and Sciences, American University of Ras Al Khaimah, Ras Al-Khaimah 10021, United Arab Emirates
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3
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Briant M, Mestdagh JM, Gaveau MA, Poisson L. Reaction dynamics within a cluster environment. Phys Chem Chem Phys 2022; 24:9807-9835. [PMID: 35441619 DOI: 10.1039/d1cp05783a] [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 perspective article reviews experimental and theoretical works where rare gas clusters and helium nanodroplets are used as a nanoreactor to investigate chemical dynamics in a solvent environment. A historical perspective is presented first followed by specific considerations on the mobility of reactants within these reaction media. The dynamical response of pure clusters and nanodroplets to photoexcitation is shortly reviewed before examining the role of the cluster (or nanodroplet) degrees of freedom in the photodynamics of the guest atoms and molecules.
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Affiliation(s)
- Marc Briant
- Université Paris-Saclay, CEA, CNRS, LIDYL, 91191, Gif-sur-Yvette, France
| | | | - Marc-André Gaveau
- Université Paris-Saclay, CEA, CNRS, LIDYL, 91191, Gif-sur-Yvette, France
| | - Lionel Poisson
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405, Orsay, France.
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4
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Kristensen HH, Kranabetter L, Schouder CA, Stapper C, Arlt J, Mudrich M, Stapelfeldt H. Quantum-State-Sensitive Detection of Alkali Dimers on Helium Nanodroplets by Laser-Induced Coulomb Explosion. PHYSICAL REVIEW LETTERS 2022; 128:093201. [PMID: 35302820 DOI: 10.1103/physrevlett.128.093201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/21/2022] [Accepted: 02/10/2022] [Indexed: 06/14/2023]
Abstract
Rubidium dimers residing on the surface of He nanodroplets are doubly ionized by an intense femtosecond laser pulse leading to fragmentation into a pair of Rb^{+} ions. We show that the kinetic energy of the Rb^{+} fragment ions can be used to identify dimers formed in either the X ^{1}Σ_{g}^{+} ground state or in the lowest-lying triplet state, a ^{3}Σ_{u}^{+}. From the experiment, we estimate the abundance ratio of dimers in the a and X states as a function of the mean droplet size and find values between 4∶1 and 5∶1. Our technique applies generally to dimers and trimers of alkali atoms, here also demonstrated for Li_{2}, Na_{2}, and K_{2}, and will enable femtosecond time-resolved measurements of their rotational and vibrational dynamics, possibly with atomic structural resolution.
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Affiliation(s)
- Henrik H Kristensen
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Lorenz Kranabetter
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Constant A Schouder
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Christoph Stapper
- Faculty of Chemistry and Pharmacy, University of Würzburg, Am Hubland, Campus Süd, D-97074 Würzburg, Germany
| | - Jacqueline Arlt
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Marcel Mudrich
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Henrik Stapelfeldt
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
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5
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Solvation of lithium ion in helium clusters: Structural properties and relative stabilities. J Mol Graph Model 2020; 98:107582. [PMID: 32200277 DOI: 10.1016/j.jmgm.2020.107582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 01/18/2023]
Abstract
Structural study and relative stabilities of Li+-doped helium clusters Li+Hen (n = 1-18) has been reported in this work using two theoretical protocols. The first one is based on the basin-hopping optimization technique, where the total energy of each cluster is described by an additive model describing Li+-He and He-He interactions. The second one is the DFT calculations, in which the initial structures are generated by ABCluster algorithm and CALYPSO software. The CSA shape was found where the first solvation shell is completed at n = 10. The relative stabilities of Li+Hen (n = 1-18) clusters have been discussed based on the variation of the binding energy, second-order difference in energy, fragmentation energy and HOMO-LUMO energy gap as a function of the cluster size. The results showed that Li+He10 is the most stable cluster. The dipole moment is calculated and showed the polar character of the Li+Hen clusters. Finally, the interatomic interactions have been examined topologically by the means of AIM and non-covalent reduced density gradient (NC-RDG) analyses.
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6
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Ghosh A, Cederbaum LS, Gokhberg K. Electron transfer mediated decay in HeLi 2 cluster: Potential energy surfaces and decay widths. J Chem Phys 2019; 150:164309. [PMID: 31042888 DOI: 10.1063/1.5082952] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Electron transfer mediated decay (ETMD) is a process responsible for double ionization of dopants in He droplets. It is initiated by producing He+ in the droplet, which is neutralized by ETMD, and has been shown to strongly enhance the dopant's double ionization cross section. The efficiency of ETMD, the spectra of emitted secondary electrons, and the character of the ionic products depend on the nuclear dynamics during the decay. To date, there has been no theoretical investigation of multimode dynamics which accompanies ETMD, which could help to understand such dynamics in a He droplet. In this article, we consider the He-Li2 cluster where an ab initio examination of multimode dynamics during the electronic decay is feasible. Moreover, this cluster can serve as a minimal model for Li2 adsorbed on the droplet's surface-a system where ETMD can be observed experimentally. In He droplets, Li2 can be formed in both the ground X1Σg + and the first excited a3Σu + states. In this article, we present ab initio potential energy surfaces of the electronic states of the He-Li2 cluster involved in ETMD, as well as the respective decay widths. We show that the structure of these surfaces and expected nuclear dynamics strongly depend on the electronic state of Li2. Thus, the overall decay rate and the appearance of the observable electron spectra will be dictated by the electronic structure of the dopant.
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Affiliation(s)
- Aryya Ghosh
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
| | - Lorenz S Cederbaum
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
| | - Kirill Gokhberg
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
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7
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Bruder L, Bangert U, Binz M, Uhl D, Vexiau R, Bouloufa-Maafa N, Dulieu O, Stienkemeier F. Coherent multidimensional spectroscopy of dilute gas-phase nanosystems. Nat Commun 2018; 9:4823. [PMID: 30446649 PMCID: PMC6240067 DOI: 10.1038/s41467-018-07292-w] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 10/25/2018] [Indexed: 12/20/2022] Open
Abstract
Two-dimensional electronic spectroscopy (2DES) is one of the most powerful spectroscopic techniques with unique sensitivity to couplings, coherence properties and real-time dynamics of a quantum system. While successfully applied to a variety of condensed phase samples, high precision experiments on isolated systems in the gas phase have been so far precluded by insufficient sensitivity. However, such experiments are essential for a precise understanding of fundamental mechanisms and to avoid misinterpretations. Here, we solve this issue by extending 2DES to isolated nanosystems in the gas phase prepared by helium nanodroplet isolation in a molecular beam-type experiment. This approach uniquely provides high flexibility in synthesizing tailored, quantum state-selected model systems of single and many-body character. In a model study of weakly-bound Rb2 and Rb3 molecules we demonstrate the method's unique capacity to elucidate interactions and dynamics in tailored quantum systems, thereby also bridging the gap to experiments in ultracold quantum science.
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Affiliation(s)
- Lukas Bruder
- Institute of Physics, University of Freiburg, 79104, Freiburg, Germany.
| | - Ulrich Bangert
- Institute of Physics, University of Freiburg, 79104, Freiburg, Germany
| | - Marcel Binz
- Institute of Physics, University of Freiburg, 79104, Freiburg, Germany
| | - Daniel Uhl
- Institute of Physics, University of Freiburg, 79104, Freiburg, Germany
| | - Romain Vexiau
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, 91405, Orsay Cedex, France
| | - Nadia Bouloufa-Maafa
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, 91405, Orsay Cedex, France
| | - Olivier Dulieu
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, 91405, Orsay Cedex, France
| | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, 79104, Freiburg, Germany.,Freiburg Institute of Advanced Studies (FRIAS), University of Freiburg, Albertstr. 19, 79194, Freiburg, Germany
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8
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Gutiérrez-Quintanilla A, Briant M, Mengesha E, Gaveau MA, Mestdagh JM, Soep B, Crépin C, Poisson L. A HElium NanoDroplet Isolation (HENDI) investigation of the weak hydrogen bonding in the propyne dimer (CH3CCH)2. Phys Chem Chem Phys 2018; 20:28658-28666. [DOI: 10.1039/c8cp04738c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A HElium Nanodroplet Isolation (HENDI) experiment was performed to explore the absorption spectra of the propyne monomer (CH3CCH), dimer and (CH3CCH)≥3 multimers in the vicinity of the CH stretch region ν1 of the monomer.
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Affiliation(s)
| | - M. Briant
- LIDYL
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay
| | - E. Mengesha
- LIDYL
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay
| | | | | | - B. Soep
- LIDYL
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay
| | - C. Crépin
- Institut des Sciences Moléculaires d'Orsay (ISMO)
- UMR 8214
- CNRS
- F-91405 Orsay
- France
| | - L. Poisson
- LIDYL
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay
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9
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Briant M, Mengesha E, Gaveau MA, Soep B, Mestdagh JM, Poisson L. Dynamics of acetylene dimers hosted in helium droplets. Phys Chem Chem Phys 2018; 20:2597-2605. [DOI: 10.1039/c7cp07741f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The CH antisymmetric stretch of the C2H2 moieties in acetylene dimers was explored over the range 3270–3290 cm−1 using the helium nanodroplet isolation (HENDI) technique.
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Affiliation(s)
- M. Briant
- LIDYL
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay
| | - E. Mengesha
- LIDYL
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay
| | | | - B. Soep
- LIDYL
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay
| | | | - L. Poisson
- LIDYL
- CEA
- CNRS
- Université Paris-Saclay
- CEA Saclay
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10
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de Lara-Castells MP, Hauser AW, Mitrushchenkov AO. Ab Initio Confirmation of a Harpoon-Type Electron Transfer in a Helium Droplet. J Phys Chem Lett 2017; 8:4284-4288. [PMID: 28841325 DOI: 10.1021/acs.jpclett.7b01910] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
An ab initio study of a long-range electron transfer or "harpoon"-type process from Cs and Cs2 to C60 in a superfluid helium droplet is presented. The heliophobic Cs or Cs2 species are initially located at the droplet surface, while the heliophilic C60 molecule is fully immersed in the droplet. First, probabilities for the electron transfer in the gas phase are calculated for reactants with velocities below the critical Landau velocity of 57 m/s to account for the superfluid helium environment. Next, reaction pathways are derived that also include the repulsive contribution from the extrusion of helium upon the approach of the two reactants. Our results are in perfect agreement with recent experimental measurements of electron ionization mass spectroscopy [ Renzler , M. ; et al., J. Chem. Phys. 2016 , 145 , 181101 ], showing a high possibility for the formation of a Cs2-C60 complex inside of the droplet through a direct harpoon-type electron transfer involving the rotation of the molecule but a negligibly low reactivity for atomic Cs.
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Affiliation(s)
| | - Andreas W Hauser
- Institute of Experimental Physics, Graz University of Technology , Petersgasse 16, 8010 Graz, Austria
| | - Alexander O Mitrushchenkov
- Laboratoire Modélisation et Simulation Multi Echelle, Université Paris-Est , MSME UMR 8208 CNRS 5 bd Descartes, 77454 Marne-la-Vallée, France
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11
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Renzler M, Daxner M, Kranabetter L, Kaiser A, Hauser AW, Ernst WE, Lindinger A, Zillich R, Scheier P, Ellis AM. Communication: Dopant-induced solvation of alkalis in liquid helium nanodroplets. J Chem Phys 2017; 145:181101. [PMID: 27846692 DOI: 10.1063/1.4967405] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Alkali metal atoms and small alkali clusters are classic heliophobes and when in contact with liquid helium they reside in a dimple on the surface. Here we show that alkalis can be induced to submerge into liquid helium when a highly polarizable co-solute, C60, is added to a helium nanodroplet. Evidence is presented that shows that all sodium clusters, and probably single Na atoms, enter the helium droplet in the presence of C60. Even clusters of cesium, an extreme heliophobe, dissolve in liquid helium when C60 is added. The sole exception is atomic Cs, which remains at the surface.
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Affiliation(s)
- Michael Renzler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Matthias Daxner
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Lorenz Kranabetter
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Alexander Kaiser
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Andreas W Hauser
- Institut für Experimentalphysik, Technische Universität Graz, Petergasse 16, A-8010 Graz, Austria
| | - Wolfgang E Ernst
- Institut für Experimentalphysik, Technische Universität Graz, Petergasse 16, A-8010 Graz, Austria
| | - Albrecht Lindinger
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Robert Zillich
- Institut für Theoretische Physik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Andrew M Ellis
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
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12
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Dehdashti-Jahromi M, Farrokhpour H. Effect of helium nanoclusters on the spectroscopic properties of embedded SF 6: Ionization, excitation and vibration. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 173:772-782. [PMID: 27794241 DOI: 10.1016/j.saa.2016.10.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 06/06/2023]
Abstract
Ionization and excitation energies, IR and Raman spectra of sulfur hexafluoride (SF6), located inside helium (He) nanoclusters with different sizes (SF6@Hen; n=20, 40, 60), were calculated. The effect of the cluster size on the spectroscopic properties of the SF6 was investigated and found that the Hen-SF6 interaction in the He clusters with large number of atoms is small so that the ionization and absorption energies of SF6 are not affected while for small He nanoclusters the Hen-SF6 interaction is more important. The effect of Hen-SF6 interaction and deformation of the fragments on the photoelectron and absorption spectra of SF6@Hen were separated theoretically and discussed in details. It was deduced that the effect of the cluster size on the IR and Raman vibrational frequencies of the SF6 is negligible for the cluster size range considered in this work. Density functional theory (DFT) employing M06-2X functional and 6-31+G(df) basis set were used for optimizing the structures of SF6@Hen. Symmetry adapted cluster-configuration interaction (SAC-CI) methodology, with the same basis set, were used to calculate the ionization and excitation energies of the SF6@Hen structures. Using the calculated ionization and absorption energies and their intensities, the photoelectron and absorption spectra of the considered SF6@Hen structures were simulated and compared with the experiment.
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Affiliation(s)
- M Dehdashti-Jahromi
- Department of Chemistry, Isfahan University of Technology, Isfahan, Iran, 84156-83111
| | - H Farrokhpour
- Department of Chemistry, Isfahan University of Technology, Isfahan, Iran, 84156-83111.
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13
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Hauser AW, de Lara-Castells MP. Spatial quenching of a molecular charge-transfer process in a quantum fluid: the Cs x-C 60 reaction in superfluid helium nanodroplets. Phys Chem Chem Phys 2017; 19:1342-1351. [PMID: 27975088 DOI: 10.1039/c6cp06858h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A recent experimental study [Renzler et al., J. Chem. Phys., 2016, 145, 181101] on superfluid helium nanodroplets reported different reactivities for Cs atoms and Cs2 dimers with C60 fullerenes inside helium droplets. Alkali metal atoms and clusters are heliophobic, therefore typically residing on the droplet surface, while fullerenes are fully immersed into the droplet. In this theoretical study, which combines standard methods of computational chemistry with orbital-free helium density functional theory, we show that the experimental findings can be interpreted in the light of a quenched electron-transfer reaction between the fullerene and the alkali dopant, which is additionally hindered by a reaction barrier stemming from the necessary extrusion of helium upon approach of the two reactants.
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Affiliation(s)
- Andreas W Hauser
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria.
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14
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Sieg A, von Vangerow J, Stienkemeier F, Dulieu O, Mudrich M. Desorption Dynamics of Rb 2 Molecules Off the Surface of Helium Nanodroplets. J Phys Chem A 2016; 120:7641-7649. [PMID: 27606714 DOI: 10.1021/acs.jpca.6b05732] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The desorption dynamics of rubidium dimers (Rb2) off the surface of helium nanodroplets induced by laser excitation is studied by employing both nanosecond and femtosecond ion imaging spectroscopy. Similarly to alkali metal atoms, we find that the Rb2 desorption process resembles the dissociation of a diatomic molecule. However, both angular and energy distributions of detected Rb2+ ions appear to be most crucially determined by the Rb2 intramolecular degrees of freedom rather than by those of the Rb2HeN complex. The pump-probe dynamics of Rb2+ is found to be slower than that of Rb+, pointing at a weaker effective guest-host repulsion for excited molecules than for single atoms.
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Affiliation(s)
- A Sieg
- Physikalisches Institut, Universität Freiburg , 79104 Freiburg, Germany
| | - J von Vangerow
- Physikalisches Institut, Universität Freiburg , 79104 Freiburg, Germany
| | - F Stienkemeier
- Physikalisches Institut, Universität Freiburg , 79104 Freiburg, Germany
| | - O Dulieu
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay , 91405 Orsay Cedex, France
| | - M Mudrich
- Physikalisches Institut, Universität Freiburg , 79104 Freiburg, Germany
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15
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Bruder L, Mudrich M, Stienkemeier F. Phase-modulated electronic wave packet interferometry reveals high resolution spectra of free Rb atoms and Rb*He molecules. Phys Chem Chem Phys 2015; 17:23877-85. [PMID: 26309123 DOI: 10.1039/c5cp03868e] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phase-modulated wave packet interferometry is combined with mass-resolved photoion detection to investigate rubidium atoms attached to helium nanodroplets in a molecular beam experiment. The spectra of atomic Rb electronic states show a vastly enhanced sensitivity and spectral resolution when compared to conventional pump-probe wave packet interferometry. Furthermore, the formation of Rb*He exciplex molecules is probed and for the first time a fully resolved vibrational spectrum for transitions between the lowest excited 5Π3/2 and the high-lying electronic states 2(2)Π, 4(2)Δ, 6(2)Σ is obtained and compared to theory. The feasibility of applying coherent multidimensional spectroscopy to dilute cold gas phase samples is demonstrated in these experiments.
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Affiliation(s)
- Lukas Bruder
- Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany.
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16
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Chen L, Zhang J, Freund WM, Kong W. Effect of kinetic energy on the doping efficiency of cesium cations into superfluid helium droplets. J Chem Phys 2015; 143:044310. [PMID: 26233132 PMCID: PMC4522010 DOI: 10.1063/1.4927471] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 07/15/2015] [Indexed: 11/14/2022] Open
Abstract
We present an experimental investigation of the effect of kinetic energy on the ion doping efficiency of superfluid helium droplets using cesium cations from a thermionic emission source. The kinetic energy of Cs(+) is controlled by the bias voltage of a collection grid collinearly arranged with the droplet beam. Efficient doping from ions with kinetic energies from 20 eV up to 480 V has been observed in different sized helium droplets. The relative ion doping efficiency is determined by both the kinetic energy of the ions and the average size of the droplet beam. At a fixed source temperature, the number of doped droplets increases with increasing grid voltage, while the relative ion doping efficiency decreases. This result implies that not all ions are captured upon encountering with a sufficiently large droplet, a deviation from the near unity doping efficiency for closed shell neutral molecules. We propose that this drop in ion doping efficiency with kinetic energy is related to the limited deceleration rate inside a helium droplet. When the source temperature changes from 14 K to 17 K, the relative ion doping efficiency decreases rapidly, perhaps due to the lack of viable sized droplets. The size distribution of the Cs(+)-doped droplet beam can be measured by deflection and by energy filtering. The observed doped droplet size is about 5 × 10(6) helium atoms when the source temperature is between 14 K and 17 K.
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Affiliation(s)
- Lei Chen
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - William M Freund
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
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17
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Benedek G, Hizhnyakov V, Toennies JP. The Response of a 3He Fermi Liquid Droplet to Vibronic Excitation of an Embedded Glyoxal Molecule. J Phys Chem A 2014; 118:6574-83. [DOI: 10.1021/jp503184d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Giorgio Benedek
- Donostia
International Physics Center (DIPC), University of the Basque Country (EHU-UPV), Paseo de Lardizàbal 4, 20018 Donostia/San Sebastian, Spain
- Dipartimento
di Scienza dei Materiali, Università di Milano-Bicocca, Via
Cozzi 53, 20125 Milano, Italy
- Max-Planck Institut für Dynamik und Selbstorganisation, Am Fassberg 17, 37077 Göttingen, Germany
| | - Vladimir Hizhnyakov
- Institute
of Physics, University of Tartu, Riia tu. 142, 202400 Tartu, Estonia
| | - J. Peter Toennies
- Max-Planck Institut für Dynamik und Selbstorganisation, Am Fassberg 17, 37077 Göttingen, Germany
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von Vangerow J, Sieg A, Stienkemeier F, Mudrich M, Leal A, Mateo D, Hernando A, Barranco M, Pi M. Desorption Dynamics of Heavy Alkali Metal Atoms (Rb, Cs) Off the Surface of Helium Nanodroplets. J Phys Chem A 2014; 118:6604-14. [DOI: 10.1021/jp503308w] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. von Vangerow
- Physikalisches
Institut, Universität Freiburg, 79104 Freiburg, Germany
| | - A. Sieg
- Physikalisches
Institut, Universität Freiburg, 79104 Freiburg, Germany
| | - F. Stienkemeier
- Physikalisches
Institut, Universität Freiburg, 79104 Freiburg, Germany
| | - M. Mudrich
- Physikalisches
Institut, Universität Freiburg, 79104 Freiburg, Germany
| | - A. Leal
- Departament
ECM, Facultat de Física and IN2UB, Universitat de Barcelona, 08028 Barcelona, Spain
| | - D. Mateo
- Departament
ECM, Facultat de Física and IN2UB, Universitat de Barcelona, 08028 Barcelona, Spain
- Department
of Chemistry and Biochemistry, California State University at Northridge, 18111 Nordhoff Street, Northridge, California 91330, United States
| | - A. Hernando
- Laboratoire
de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - M. Barranco
- Departament
ECM, Facultat de Física and IN2UB, Universitat de Barcelona, 08028 Barcelona, Spain
| | - M. Pi
- Departament
ECM, Facultat de Física and IN2UB, Universitat de Barcelona, 08028 Barcelona, Spain
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20
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Lackner F, Poms J, Krois G, Pototschnig JV, Ernst WE. Spectroscopy of lithium atoms and molecules on helium nanodroplets. J Phys Chem A 2013; 117:11866-73. [PMID: 23895106 PMCID: PMC3839407 DOI: 10.1021/jp4030238] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
We
report on the spectroscopic investigation of lithium atoms and
lithium dimers in their triplet manifold on the surface of helium
nanodroplets (HeN). We present the excitation spectrum
of the 3p ← 2s and 3d ← 2s two-photon transitions for
single Li atoms on HeN. The atoms are excited from the
2S(Σ) ground state into Δ, Π, and Σ pseudodiatomic
molecular substates. Excitation spectra are recorded by resonance
enhanced multiphoton ionization time-of-flight (REMPI-TOF) mass spectroscopy,
which allows an investigation of the exciplex (Li*–Hem, m = 1–3) formation process
in the Li–HeN system. Electronic states are shifted
and broadened with respect to free atom states, which is explained
within the pseudodiatomic model. The assignment is assisted by theoretical
calculations, which are based on the Orsay–Trento density functional
where the interaction between the helium droplet and the lithium atom
is introduced by a pairwise additive approach. When a droplet is doped
with more than one alkali atom, the fragility of the alkali–HeN systems leads preferably to the formation of high-spin molecules
on the droplets. We use this property of helium nanodroplets for the
preparation of Li dimers in their triplet ground state (13Σu+).
The excitation spectrum of the 23Πg(ν′
= 0–11) ← 13Σu+(ν″ = 0) transition is presented.
The interaction between the molecule and the droplet manifests in
a broadening of the transitions with a characteristic asymmetric form.
The broadening extends to the blue side of each vibronic level, which
is caused by the simultaneous excitation of the molecule and vibrations
of the droplet (phonons). The two isotopes of Li form 6Li2 and 7Li2 as well as isotope
mixed 6Li7Li molecules on the droplet surface.
By using REMPI-TOF mass spectroscopy, isotope-dependent effects could
be studied.
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Affiliation(s)
- Florian Lackner
- Institute of Experimental Physics, Graz University of Technology , Petersgasse 16, A-8010 Graz, Austria/EU
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21
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Benedek G, Hizhnyakov V. Fermi sea excitations in the optical spectrum of a doped 3He droplet. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.07.065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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23
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Hizhnyakov V. Zero-phonon lines of systems with different dimensions and unconventional vibronic interactions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:104011. [PMID: 22353367 DOI: 10.1088/0953-8984/24/10/104011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The standard theory of the optical spectra of impurity centres in solids predicts the Lorentzian shape of the zero-phonon lines to have temperature-dependent position and width. However, in recent years different systems, including ones of reduced dimension, have been found, in which remarkable deviations from the standard laws have been observed. Generalizations of the theory to these systems are presented. Among other things, the quantum liquid 3He doped by optical centres is considered.
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Affiliation(s)
- V Hizhnyakov
- Institute of Physics, University of Tartu, Tartu, Estonia.
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24
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López-Durán D, Rodríguez-Cantano R, González-Lezana T, Delgado-Barrio G, Villarreal P, Yurtsever E, Gianturco FA. Weakly bound finite systems: (⁴He)N-Rb₂(³Σu), clustering structures from a quantum Monte Carlo approach. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:104014. [PMID: 22353432 DOI: 10.1088/0953-8984/24/10/104014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report here ((4)He)(N)-Rb(2)((3)Σ(u)) complexes, 2 ≤ N ≤ 20, analysed through a quantum diffusion Monte Carlo stochastic approach. The calculations show that the spin stretched dimer molecule is bound outside the pure He sub-complex, due to the stronger He-He potential as compared with the He-Rb(2) interaction, while the rare gas atom moiety presents, in turn, a shell-like structure with ten He adatoms completing the first shell. Our results agree with previous findings on this and similarly weakly interacting systems.
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Affiliation(s)
- D López-Durán
- Instituto de Física Fundamental, CSIC, Serrano 123, 28006 Madrid, Spain
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25
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Ratschek M, Koch M, Ernst WE. Doping helium nanodroplets with high temperature metals: Formation of chromium clusters. J Chem Phys 2012; 136:104201. [PMID: 22423831 DOI: 10.1063/1.3692330] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Martin Ratschek
- Institute of Experimental Physics, TU Graz, Petersgasse 16, A-8010 Graz, Austria
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26
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Tacconi M, Bovino S, Gianturco FA. Direct and inverse reactions of LiH+ with He(1S) from quantum calculations: mechanisms and rates. Phys Chem Chem Phys 2011; 14:637-45. [PMID: 22086258 DOI: 10.1039/c1cp22315a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The gas-phase reaction of LiH(+) (X(2)Σ) with He((1)S) atoms, yielding Li(+)He with a small endothermicity for the rotovibrational ground state of the reagents, is analysed using the quantum reactive approach that employs the Negative Imaginary Potential (NIP) scheme discussed earlier in the literature. The dependence of low-T rates on the initial vibrational state of LiH(+) is analysed and the role of low-energy Feshbach resonances is also discussed. The inverse destruction reaction of LiHe(+), a markedly exothermic process, is also investigated and the rates are computed in the same range of temperatures. The possible roles of these reactions in early universe astrophysical networks, in He droplets environments or in cold traps are briefly discussed.
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Affiliation(s)
- M Tacconi
- Department of Chemistry, Sapienza University of Rome, Rome, Italy
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27
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Guillon G, Zanchet A, Leino M, Viel A, Zillich RE. Theoretical Study of Rb2 in HeN: Potential Energy Surface and Monte Carlo Simulations. J Phys Chem A 2011; 115:6918-26. [DOI: 10.1021/jp112053b] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Grégroire Guillon
- Institut de Physique de Rennes, UMR 6251, CNRS & Université de Rennes I, F-35042 Rennes, France
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28
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Brahms N, Tscherbul TV, Zhang P, Kłos J, Sadeghpour HR, Dalgarno A, Doyle JM, Walker TG. Formation of van der Waals molecules in buffer-gas-cooled magnetic traps [corrected]. PHYSICAL REVIEW LETTERS 2010; 105:033001. [PMID: 20867761 DOI: 10.1103/physrevlett.105.033001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 05/29/2010] [Indexed: 05/29/2023]
Abstract
We predict that a large class of helium-containing cold polar molecules form readily in a cryogenic buffer gas, achieving densities as high as 10(12) cm(-3). We explore the spin relaxation of these molecules in buffer-gas-loaded magnetic traps and identify a loss mechanism based on Landau-Zener transitions arising from the anisotropic hyperfine interaction. Our results show that the recently observed strong T(-6) thermal dependence of the spin-change rate of silver (Ag) trapped in dense (3)He is accounted for by the formation and spin change of Ag(3)He van der Waals molecules, thus providing indirect evidence for molecular formation in a buffer-gas trap.
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Affiliation(s)
- N Brahms
- Department of Physics, University of California, Berkeley, California 97420, USA
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29
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Bovino S, Coccia E, Bodo E, Lopez-Durán D, Gianturco FA. Spin-driven structural effects in alkali doped (4)He clusters from quantum calculations. J Chem Phys 2009; 130:224903. [PMID: 19530785 DOI: 10.1063/1.3147466] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this paper, we carry out variational Monte Carlo and diffusion Monte Carlo (DMC) calculations for Li(2)((1)Sigma(g) (+))((4)He)(N) and Li(2)((3)Sigma(u) (+))((4)He)(N) with N up to 30 and discuss in detail the results of our computations. After a comparison between our DMC energies with the "exact" discrete variable representation values for the species with one (4)He, in order to test the quality of our computations at 0 K, we analyze the structural features of the whole range of doped clusters. We find that both species reside on the droplet surface, but that their orientation is spin driven, i.e., the singlet molecule is perpendicular and the triplet one is parallel to the droplet's surface. We have also computed quantum vibrational relaxation rates for both dimers in collision with a single (4)He and we find them to differ by orders of magnitude at the estimated surface temperature. Our results therefore confirm the findings from a great number of experimental data present in the current literature and provide one of the first attempts at giving an accurate, fully quantum picture for the nanoscopic properties of alkali dimers in (4)He clusters.
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Affiliation(s)
- S Bovino
- Department of Chemistry and CNISM, The University of Rome Sapienza, P.le A. Moro 5, 00185 Rome, Italy
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30
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Stiles PL, Douberly GE, Miller RE. High-resolution infrared spectroscopy of Mg-HF and Mg-(HF)2 solvated in helium nanodroplets. J Chem Phys 2009; 130:184313. [PMID: 19449927 DOI: 10.1063/1.3137122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High-resolution infrared (IR) spectroscopy is used to investigate the Mg-HF and Mg-(HF)(2) van der Waals complexes. Both complexes are formed and probed within helium nanodroplets. Rotationally resolved zero-field and Stark spectra are assigned to a linear binary complex composed of a Mg atom bound to the hydrogen end of the HF molecule. Although high level ab initio calculations predict a fluorine bonded complex, none of the observed IR bands can be assigned to this complex. The collocation method is employed to determine the bound states on the two-dimensional intermolecular Mg-HF potential energy surface. The ground and first excited state wave functions for this potential surface have zero amplitude in the well corresponding to the fluorine bonded complex, consistent with experiment. The two HF stretching bands of the Mg-(HF)(2) complex are observed and assigned using a combination of the spectral symmetry, ab initio calculations, pick-up cell pressure dependencies, and dipole moment measurements. Comparisons with the helium solvated HF dimer show large changes to the HF stretching frequencies upon the addition of a single Mg atom to the hydrogen side of (HF)(2).
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Affiliation(s)
- Paul L Stiles
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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31
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Szalewicz K. Interplay between theory and experiment in investigations of molecules embedded in superfluid helium nanodroplets†. INT REV PHYS CHEM 2008. [DOI: 10.1080/01442350801933485] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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32
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Patkowski K, Podeszwa R, Szalewicz K. Interactions in Diatomic Dimers Involving Closed-Shell Metals. J Phys Chem A 2007; 111:12822-38. [DOI: 10.1021/jp076412c] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Konrad Patkowski
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716
| | - Rafał Podeszwa
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716
| | - Krzysztof Szalewicz
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716
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33
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Douberly GE, Miller RE. Rotational Dynamics of HCN−M (M = Na, K, Rb, Cs) van der Waals Complexes Formed on the Surface of Helium Nanodroplets. J Phys Chem A 2007; 111:7292-302. [PMID: 17602450 DOI: 10.1021/jp070042a] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Infrared laser spectroscopy was used to probe the unique rotational dynamics of the HCN-M (M = Na, K, Rb, Cs) complexes formed on the surface of helium droplets. The nu1 CH stretch ro-vibrational spectra were measured revealing what appears to be the P and R contours of a nearly rigid linear rotor. To simulate the linear molecule spectra, given a rotational temperature of 0.37 K, effective moments of inertia, IB, were required to be 10(4)-10(5) amu.A2 larger than the ab initio predicted values. The large moments of inertia were found to be strongly dependent on both the mass of the complex and the size of the helium droplet, consistent with a model where the dopant is located in a dimple site on the surface of the droplet. In this model, the moment of inertia is representative of the rotational motion of the dopant on the surface about an inertial axis through the center of the droplet.
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Affiliation(s)
- Gary E Douberly
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
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34
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Claas P, Droppelmann G, Schulz CP, Mudrich M, Stienkemeier F. Wave Packet Dynamics in Triplet States of Na2 Attached to Helium Nanodroplets. J Phys Chem A 2007; 111:7537-41. [PMID: 17461563 DOI: 10.1021/jp070893i] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dynamics of vibrational wave packets excited in Na2 dimers in the triplet ground and excited states is investigated by means of helium nanodroplet isolation (HENDI) combined with femtosecond pump-probe spectroscopy. Different pathways in the employed resonant multiphoton ionization scheme are identified. Within the precision of the method, the wave packet dynamics appears to be unperturbed by the helium droplet environment.
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Affiliation(s)
- Patrick Claas
- Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld, Germany
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35
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Fárník M, Toennies JP. Ion-molecule reactions in 4He droplets: flying nano-cryo-reactors. J Chem Phys 2007; 122:14307. [PMID: 15638659 DOI: 10.1063/1.1815272] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Ion-molecule reactions are studied inside large (approximately equal to 10(4) atoms) very cold (0.37 K) superfluid (4)He droplets by mass spectrometric detection of the product ions. He+ ions initially formed inside the droplets by electron impact ionization undergo charge transfer with either embedded D(2), N(2), or CH(4). For D(2) this charge transfer process was studied in detail by varying the pickup pressure. For either N(2) or CH(4) the reagent ions were formed by this charge transfer and the reaction pathways of the secondary reactions N(2) (+)+D(2), CH(4) (+)+D(2), and CH(3) (+)+D(2) each with an additionally embedded D(2) molecule were also determined from the pickup pressure dependencies. In several cases, notably He.N(2) (+) and CH(3)D(2) (+) reaction intermediates are observed. The analysis is facilitated by the tendency for molecular ion products to appear without (or with only very few) attached He atoms whereas the atomic ion products usually appear in the mass spectra with several attached He atoms, e.g., He(m).D+ ions with up to m=19.
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Affiliation(s)
- Michal Fárník
- Max-Planck Institut für Strömungsforschung, Bunsenstrasse 10, D-37073 Göttingen, Germany.
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36
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Merritt JM, Küpper J, Miller RE. A high-resolution infrared spectroscopic investigation of the halogen atom–HCN entrance channel complexes solvated in superfluid helium droplets. Phys Chem Chem Phys 2007; 9:401-16. [PMID: 17199157 DOI: 10.1039/b611340k] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rotationally resolved infrared spectra are reported for the X-HCN (X = Cl, Br, I) binary complexes solvated in helium nanodroplets. These results are directly compared with those obtained previously for the corresponding X-HF complexes [J. M. Merritt, J. Küpper and R. E. Miller, Phys. Chem. Chem. Phys., 2005, 7, 67]. For bromine and iodine atoms complexed with HCN, two linear structures are observed and assigned to the (2)Sigma(1/2) and (2)Pi(3/2) ground electronic states of the nitrogen and hydrogen bound geometries, respectively. Experiments for HCN + chlorine atoms give rise to only a single band which is attributed to the nitrogen bound isomer. That the hydrogen bound isomer is not stabilized is rationalized in terms of a lowering of the isomerization barrier by spin-orbit coupling. Theoretical calculations with and without spin-orbit coupling have also been performed and are compared with our experimental results. The possibility of stabilizing high-energy structures containing multiple radicals is discussed, motivated by preliminary spectroscopic evidence for the di-radical Br-HCCCN-Br complex. Spectra for the corresponding molecular halogen HCN-X(2) complexes are also presented.
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Affiliation(s)
- Jeremy M Merritt
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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37
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Tiggesbäumker J, Stienkemeier F. Formation and properties of metal clusters isolated in helium droplets. Phys Chem Chem Phys 2007; 9:4748-70. [PMID: 17712454 DOI: 10.1039/b703575f] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The unique conditions forming atomic and molecular complexes and clusters using superfluid helium nanodroplets have opened up an innovative route for studying the physical and chemical properties of matter on the nanoscale. This review summarizes the specific characteristics of the formation of atomic clusters partly generated far from equilibrium in the helium environment. Special emphasis is on the optical response, electronic properties as well as dynamical processes which are mostly affected by the surrounding quantum matrix. Experiments include the optical induced response of isolated cluster systems in helium under quite different excitation conditions ranging from the linear regime up to the violent interaction with a strong laser field leading to Coulomb explosion and the generation of highly charged atomic fragments. The variety of results on the outstanding properties in the quantum size regime highlights the peculiar capabilities of helium nanodroplet isolation spectroscopy.
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38
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Choi MY, Douberly GE, Falconer TM, Lewis WK, Lindsay CM, Merritt JM, Stiles PL, Miller RE. Infrared spectroscopy of helium nanodroplets: novel methods for physics and chemistry. INT REV PHYS CHEM 2006. [DOI: 10.1080/01442350600625092] [Citation(s) in RCA: 327] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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39
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Bünermann O, Mudrich M, Weidemüller M, Stienkemeier F. Spectroscopy of Cs attached to helium nanodroplets. J Chem Phys 2004; 121:8880-6. [PMID: 15527352 DOI: 10.1063/1.1805508] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cesium oligomers are formed on helium nanodroplets which are doped with one or a few Cs atoms. The monomer absorption of the first electronic p<--s transition upon laser excitation is probed. Spectra employing laser-induced fluorescence, beam depletion, and resonant photoionization are compared. In particular, mass-resolved photoionization allows us to specifically probe excitation induced processes such as, e.g., the formation of cesium-helium exciplexes. Absorption spectra of Cs dimers and trimers are recorded in the spectral region accessible by a Ti:sapphire laser. Assignment of dimer spectra is achieved by comparison with model calculations based on ab initio potentials. Electronic absorption lines of Cs trimers are attributed to transitions in the quartet manifold.
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Affiliation(s)
- O Bünermann
- Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
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40
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Bodo E, Sebastianelli F, Gianturco FA, Yurtsever E, Yurtsever M. Ab initio quantum dynamics with very weak van der Waals interactions: Structure and stability of small Li2(1Sigmag+)-(He)n clusters. J Chem Phys 2004; 120:9160-6. [PMID: 15267852 DOI: 10.1063/1.1701834] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The potential energy surface (PES) for the interaction between Li2(1Sigmag+) and 4He has been computed using an accurate, post-Hartree-Fock quantum calculation for its ground electronic state. The orientational anisotropy of the forces and the interplay between repulsive and attractive effects within the PES are analyzed to extract information on the possible existence of bound states in the triatomic system. The structures of a few of the Li2(He)n small clusters are examined by comparing a classical approach with a full quantum one to generate bound configurations and to extract information on the possible spatial arrangements of the smaller clusters via à vis the location of the Li2 dopant. Some significant consequences on the Li2 behavior in larger clusters and droplets are drawn from the above findings.
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Affiliation(s)
- E Bodo
- Department of Chemistry and INFM, University of Rome La Sapienza, Italy
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Ancilotto F, Barranco M, Pi M. Probing vortices in 4He nanodroplets. PHYSICAL REVIEW LETTERS 2003; 91:105302. [PMID: 14525486 DOI: 10.1103/physrevlett.91.105302] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Indexed: 05/24/2023]
Abstract
We present static and dynamical properties of linear vortices in 4He droplets obtained from density functional calculations. By comparing the adsorption properties of different atomic impurities embedded in pure droplets and in droplets where a quantized vortex has been created, we suggest that Ca atoms should be the dopant of choice to detect vortices by means of spectroscopic experiments.
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Küpper J, Merritt JM, Miller RE. Free radicals in superfluid liquid helium nanodroplets: A pyrolysis source for the production of propargyl radical. J Chem Phys 2002. [DOI: 10.1063/1.1484104] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Hartmann M, Lindinger A, Peter Toennies J, Vilesov AF. The phonon wings in the (S1 ← S0) spectra of tetracene, pentacene, porphin and phthalocyanine in liquid helium droplets. Phys Chem Chem Phys 2002. [DOI: 10.1039/b203249j] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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45
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Schulz CP, Claas P, Stienkemeier F. Formation of K*He exciplexes on the surface of helium nanodroplets studied in real time. PHYSICAL REVIEW LETTERS 2001; 87:153401. [PMID: 11580696 DOI: 10.1103/physrevlett.87.153401] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2001] [Indexed: 05/23/2023]
Abstract
Superfluid helium nanodroplets are doped with potassium atoms to form complexes with the alkali atom residing on the surface of the droplets. Dispersed laser-induced fluorescence spectra of such systems already revealed the formation of M(*)He ( M = Na,K) exciplexes upon electronic excitation [Reho et al., Faraday Discuss. 108, 161 (1997)]. By means of femtosecond pump-probe spectroscopy, this formation process now is followed in real time. We find K(*)He(n = 1) to be formed within 180 fs. Furthermore, the existence of exciplexes with n>1 is quantified suggesting that the first ring around the potassium atom contains four helium atoms.
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Affiliation(s)
- C P Schulz
- Max-Born-Institut, Max-Born-Strasse 2a, D-12489 Berlin, Germany
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Hartmann M, Lindinger A, Toennies JP, Vilesov AF. Hole-Burning Studies of the Splitting in the Ground and Excited Vibronic States of Tetracene in Helium Droplets. J Phys Chem A 2001. [DOI: 10.1021/jp003600t] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthias Hartmann
- Max-Planck-Institut für Strömungsforschung, Bunsenstrasse 10, 37073 Göttingen, Germany
| | - Albrecht Lindinger
- Max-Planck-Institut für Strömungsforschung, Bunsenstrasse 10, 37073 Göttingen, Germany
| | - J. Peter Toennies
- Max-Planck-Institut für Strömungsforschung, Bunsenstrasse 10, 37073 Göttingen, Germany
| | - Andrej F. Vilesov
- Max-Planck-Institut für Strömungsforschung, Bunsenstrasse 10, 37073 Göttingen, Germany
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Brühl FR, Trasca RA, Ernst WE. Rb–He exciplex formation on helium nanodroplets. J Chem Phys 2001. [DOI: 10.1063/1.1410118] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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48
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Brühl FR, Miron RA, Ernst WE. Triplet states of rubidium dimers on helium nanodroplets. J Chem Phys 2001. [DOI: 10.1063/1.1418747] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Paesani F, Gianturco FA, Lewerenz M, Toennies JP. A stochastic study of microsolvation. I. Structures of CO in small argon clusters. J Chem Phys 1999. [DOI: 10.1063/1.479983] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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