1
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Asmussen JD, Sishodia K, Bastian B, Abid AR, Ben Ltaief L, Pedersen HB, De S, Medina C, Pal N, Richter R, Fennel T, Krishnan S, Mudrich M. Electron energy loss and angular asymmetry induced by elastic scattering in superfluid helium nanodroplets. NANOSCALE 2023; 15:14025-14031. [PMID: 37559557 DOI: 10.1039/d3nr03295g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Helium nanodroplets are ideal model systems to unravel the complex interaction of condensed matter with ionizing radiation. Here we study the effect of purely elastic electron scattering on angular and energy distributions of photoelectrons emitted from He nanodroplets of variable size (10-109 atoms per droplets). For large droplets, photoelectrons develop a pronounced anisotropy along the incident light beam due to a shadowing effect within the droplets. In contrast, the detected photoelectron spectra are only weakly perturbed. This opens up possibilities for photoelectron spectroscopy of dopants embedded in droplets provided they are smaller than the penetration depth of the light and the trapping range of emitted electrons in liquid helium.
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Affiliation(s)
- Jakob D Asmussen
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | - Keshav Sishodia
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, India
| | - Björn Bastian
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | - Abdul R Abid
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | | | | | - Subhendu De
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, India
| | | | | | | | | | - Sivarama Krishnan
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, India
| | - Marcel Mudrich
- Department of Physics and Astronomy, Aarhus University, Denmark.
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2
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Hauser AW, Havenith M, Koch M, Sterrer M. Festschrift for Wolfgang E. Ernst - electronic and nuclear dynamics and their interplay in molecules, clusters and on surfaces. Phys Chem Chem Phys 2023; 25:11880-11882. [PMID: 36880607 DOI: 10.1039/d3cp90052e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Guest editors, Andreas W. Hauser, Martina Havenith, Markus Koch and Martin Sterrer, introduce this themed issue dedicated to Professor Wolfgang E. Ernst on the occasion of his 70th birthday.
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Affiliation(s)
- Andreas W Hauser
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria.
| | - Martina Havenith
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany.
| | - Markus Koch
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria.
| | - Martin Sterrer
- Institute of Physics, University of Graz, 8010 Graz, Austria.
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3
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Zhou L, Hu X, Peng Y, Qiang J, Lu P, Lin K, Pan S, Gong X, Jiang W, Jiang Z, Lu C, Ni H, Jin C, Lu R, Wu Y, Wang J, Wu J. Enhancing Strong-Field Dissociation of H_{2}^{+} in Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2023; 130:033201. [PMID: 36763404 DOI: 10.1103/physrevlett.130.033201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 12/15/2022] [Indexed: 06/18/2023]
Abstract
We investigate the above-threshold multiphoton ionization of H_{2} embedded in superfluid He nanodroplets driven by ultraviolet femtosecond laser pulses. We find that the surrounding He atoms enhance the dissociation of in-droplet H_{2}^{+} from lower vibrational states as compared to that of isolated gas-phase molecules. As a result, the discrete peaks in the photoelectron energy spectrum correlated with the HHe^{+} from the dissociative in-droplet molecule shift to higher energies. Based on the electron-nuclear correlation, the photoelectrons with higher energies are correlated to the nuclei of the low-vibrationally excited molecular ion as the nuclei share less photon energy. Our time-dependent nuclear wave packet quantum simulation using a simplified He-H_{2}^{+} system confirms the joint contribution of the driving laser field and the neighboring He atoms to the dissociation dynamics of the solute molecular ion. The results strengthen our understanding of the role of the environment on light-induced ultrafast dynamics of molecules.
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Affiliation(s)
- Lianrong Zhou
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Xiaoqing Hu
- Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
| | - Yigeng Peng
- Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Junjie Qiang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Peifen Lu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Kang Lin
- Institut für Kernphysik, Goethe-Universität Frankfurt am Main, Frankfurt am Main 60438, Germany
| | - Shengzhe Pan
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Xiaochun Gong
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Wenyu Jiang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Zhejun Jiang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Chenxu Lu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Hongcheng Ni
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Cheng Jin
- Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Ruifeng Lu
- Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Yong Wu
- Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
- HEDPS, Center of Applied Physics and Technology, Peking University, Beijing 10084, China
| | - Jianguo Wang
- Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
| | - Jian Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Shanxi 030006, China
- Chongqing Key Laboratory of Precision Optics, Chongqing Institute of East China Normal University, Chongqing 401121, China
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4
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Treiber L, Kanya R, Kitzler-Zeiler M, Koch M. Dynamics of Above-Threshold Ionization and Laser-Assisted Electron Scattering inside Helium Nanodroplets. J Phys Chem A 2022; 126:8380-8387. [PMID: 36384271 PMCID: PMC9677425 DOI: 10.1021/acs.jpca.2c05410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
![]()
Laser-assisted electron scattering (LAES) is a fundamental
three
body interaction process that enables energy transfer between electrons
and photons in the presence of matter. Here, we focus on the multiscattering
regime of electrons generated by above-threshold ionization (ATI)
of In atoms inside a high-density nanostructure, helium nanodroplets
(HeN) of ∼40 Å radius. The stochastic nature
of the multiscattering regime results in photoelectron spectra independent
of laser polarization. Numerical simulations via tunnel-type ionization
followed by applying the Kroll–Watson approximation for LAES
are in agreement with experimental spectra and yield a mechanistic
description of electron generation and the LAES energy modulation
processes. We find a negligible influence of the electron start position
inside the helium droplet on the simulated electron energy spectrum.
Further, our simulations shine light on the interplay of electron
time of birth, number of LAES gain/loss events, and final kinetic
energy; early ionization leads to the largest number of scattering
events and thereby the highest electron kinetic energy.
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Affiliation(s)
- Leonhard Treiber
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010Graz, Austria
| | - Reika Kanya
- Department of Chemistry, Faculty of Science, Tokyo Metropolitan University, 1-1 minami-Osawa, Hachioji-shi, Tokyo192-0397, Japan
- JST PRESTO, 1-1 minami-Osawa, Hachioji-shi, Tokyo192-0397, Japan
| | - Markus Kitzler-Zeiler
- Photonics Institute, Technische Universität Wien, Gusshausstrasse 27-29, 1040Vienna, Austria
| | - Markus Koch
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010Graz, Austria
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5
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Vilà A, González M. Quantum dynamics of the Br 2 (B-excited state) photodissociation in superfluid helium nanodroplets: importance of the recombination process. Phys Chem Chem Phys 2022; 24:24353-24361. [PMID: 36178095 DOI: 10.1039/d2cp02984g] [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
We have studied the Br2 photodissociation dynamics (B ← X electronic transition) of Br2(v = 0, X)@(4He)N doped nanodroplets (T = 0.37 K) at zero angular momentum, with N in the 100-1000 interval. To do this, we have used a quantum mechanical hybrid strategy proposed by us and, as far as we know, this is the second quantum dynamics study available on the photodissociation of molecules in superfluid helium nanodroplets. While the results obtained for some properties are qualitatively similar to those reported previously by us for the Cl2(B ← X) related case (in particular, the oscillating Br final velocity distribution which also arises from quantum interferences), large differences are evident in three key properties: the photodissociation mechanism and probability and the time scale of the process. This can be interpreted on the basis of the significantly lower excitation energy achieved by the Br2(B ← X) transition and the higher reduced mass of Br-Br in comparison to the chlorine case. The Br2(B) photodissociation dynamics is significantly more complex than that of Cl2(B) and leads to the fragmentation of the initial wave packet. Thus, the probability of non-dissociation is equal to 17, 18, 51, 85 and 100% for N = 100, 200, 300, 500 and 1000, respectively, while for chlorine this probability is equal to zero. In spite of the very large experimental difficulties that exist for obtaining nanodroplets with a well defined size, we hope that these results will encourage experimentalists to investigate these interesting systems.
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Affiliation(s)
- Arnau Vilà
- Departament de Ciència dels Materials i Química Física and IQTC, Universitat de Barcelona, Martí i Franquès, 1-11, 08028 Barcelona, Spain.
| | - Miguel González
- Departament de Ciència dels Materials i Química Física and IQTC, Universitat de Barcelona, Martí i Franquès, 1-11, 08028 Barcelona, Spain.
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6
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High-resolution two-dimensional electronic spectroscopy reveals the homogeneous line profile of chromophores solvated in nanoclusters. Nat Commun 2022; 13:3350. [PMID: 35688839 PMCID: PMC9187667 DOI: 10.1038/s41467-022-31021-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 05/24/2022] [Indexed: 11/16/2022] Open
Abstract
Doped clusters in the gas phase provide nanoconfined model systems for the study of system-bath interactions. To gain insight into interaction mechanisms between chromophores and their environment, the ensemble inhomogeneity has to be lifted and the homogeneous line profile must be accessed. However, such measurements are very challenging at the low particle densities and low signal levels in cluster beam experiments. Here, we dope cryogenic rare-gas clusters with phthalocyanine molecules and apply action-detected two-dimensional electronic spectroscopy to gain insight into the local molecule-cluster environment for solid and superfluid cluster species. The high-resolution homogeneous linewidth analysis provides a benchmark for the theoretical modelling of binding configurations and shows a promising route for high-resolution molecular two-dimensional spectroscopy. Understanding the interaction of single chromophores with nanoparticles remains a challenging task in nanoscience. Here the authors provide insight into the interaction between isolated base-free phthalocyanine molecules and He and Ne nanoclusters in the gas phase using high-resolution two-dimensional spectroscopy.
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7
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Asmussen JD, Michiels R, Bangert U, Sisourat N, Binz M, Bruder L, Danailov M, Di Fraia M, Feifel R, Giannessi L, Plekan O, Prince KC, Squibb RJ, Uhl D, Wituschek A, Zangrando M, Callegari C, Stienkemeier F, Mudrich M. Time-Resolved Ultrafast Interatomic Coulombic Decay in Superexcited Sodium-Doped Helium Nanodroplets. J Phys Chem Lett 2022; 13:4470-4478. [PMID: 35561339 DOI: 10.1021/acs.jpclett.2c00645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The autoionization dynamics of superexcited superfluid He nanodroplets doped with Na atoms is studied by extreme-ultraviolet (XUV) time-resolved electron spectroscopy. Following excitation into the higher-lying droplet absorption band, the droplet relaxes into the lowest metastable atomic 1s2s 1,3S states from which interatomic Coulombic decay (ICD) takes place either between two excited He atoms or between an excited He atom and a Na atom attached to the droplet surface. Four main ICD channels are identified, and their decay times are determined by varying the delay between the XUV pulse and a UV pulse that ionizes the initial excited state and thereby quenches ICD. The decay times for the different channels all fall in the range of ∼1 ps, indicating that the ICD dynamics are mainly determined by the droplet environment. A periodic modulation of the transient ICD signals is tentatively attributed to the oscillation of the bubble forming around the localized He excitation.
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Affiliation(s)
- Jakob D Asmussen
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Rupert Michiels
- Institute of Physics, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Ulrich Bangert
- Institute of Physics, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Nicolas Sisourat
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique Matière et Rayonnement, 75005 Paris, France
| | - Marcel Binz
- Institute of Physics, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Lukas Bruder
- Institute of Physics, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | | | | | - Raimund Feifel
- Department of Physics, University of Gothenburg, 41133 Gothenburg, Sweden
| | - Luca Giannessi
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza TS, Italy
| | - Oksana Plekan
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza TS, Italy
| | - Kevin C Prince
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza TS, Italy
| | - Richard J Squibb
- Department of Physics, University of Gothenburg, 41133 Gothenburg, Sweden
| | - Daniel Uhl
- Institute of Physics, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Andreas Wituschek
- Institute of Physics, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Marco Zangrando
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza TS, Italy
| | - Carlo Callegari
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza TS, Italy
| | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Marcel Mudrich
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
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8
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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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9
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Solling TI. Nonstatistical Photoinduced Processes in Gaseous Organic Molecules. ACS OMEGA 2021; 6:29325-29344. [PMID: 34778606 PMCID: PMC8581993 DOI: 10.1021/acsomega.1c04035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Indexed: 05/26/2023]
Abstract
Processes that proceed in femtoseconds are usually referred to as being ultrafast, and they are investigated in experiments that involve laser pulses with femtosecond duration in so-called pump probe schemes, where a light pulse triggers a molecular process and a second light pulse interrogates the temporal evolution of the molecular population. The focus of this review is on the reactivity patterns that arise when energy is not equally distributed on all the available degrees of freedom as a consequence of the very short time scale in play and on how the localization of internal energy in a specific mode can be thought of as directing a process toward (or away from) a certain outcome. The nonstatistical aspects are illustrated with examples from photophysics and photochemistry for a range of organic molecules. The processes are initiated by a variety of nuclear motions that are all governed by the energy gradients in the Franck-Condon region. Essentially, the molecules will start to adapt to the new electronic environment on the excited state to eventually reach the equilibrium structure. It is this structural change that is enabling an ultrafast electronic transition in cases where the nuclear motion leads to a transition point with significant coupling between to electronic states and to ultrafast reaction if there is a coupling to a reactive mode at the transition point between the involved states. With the knowledge of the relation between electronic excitation and equilibrium structure, it is possible to predict how the nuclei move after excitation and often whether an ultrafast (and inherently nonstatistical) electronic transition or even a bond breakage will take place. In addition to the understanding of how nonstatistical photoinduced processes proceed from a given excited state, it has been found that randomization of the energy does not even always take place when the molecule takes part in processes that are normally considered statistical, such as for example nonradiative transitions between excited states. This means that energy can be localized in a specific degree of freedom on a state other than the one that is initially prepared. This is a finding that could kickoff the ultimate dream in applied photochemistry; namely light excitation that leads to the rupture of a specific bond.
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Affiliation(s)
- Theis I. Solling
- Center for Integrative Petroleum
Research, King Fahd University of Petroleum
& Minerals, Dhahran, 31261, Saudi Arabia
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10
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Asmussen JD, Michiels R, Dulitz K, Ngai A, Bangert U, Barranco M, Binz M, Bruder L, Danailov M, Di Fraia M, Eloranta J, Feifel R, Giannessi L, Pi M, Plekan O, Prince KC, Squibb RJ, Uhl D, Wituschek A, Zangrando M, Callegari C, Stienkemeier F, Mudrich M. Unravelling the full relaxation dynamics of superexcited helium nanodroplets. Phys Chem Chem Phys 2021; 23:15138-15149. [PMID: 34259254 DOI: 10.1039/d1cp01041g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The relaxation dynamics of superexcited superfluid He nanodroplets is thoroughly investigated by means of extreme-ultraviolet (XUV) femtosecond electron and ion spectroscopy complemented by time-dependent density functional theory (TDDFT). Three main paths leading to the emission of electrons and ions are identified: droplet autoionization, pump-probe photoionization, and autoionization induced by re-excitation of droplets relaxing into levels below the droplet ionization threshold. The most abundant product ions are He2+, generated by droplet autoionization and by photoionization of droplet-bound excited He atoms. He+ appear with some pump-probe delay as a result of the ejection He atoms in their lowest excited states from the droplets. The state-resolved time-dependent photoelectron spectra reveal that intermediate excited states of the droplets are populated in the course of the relaxation, terminating in the lowest-lying metastable singlet and triplet He atomic states. The slightly faster relaxation of the triplet state compared to the singlet state is in agreement with the simulation showing faster formation of a bubble around a He atom in the triplet state.
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Affiliation(s)
- Jakob D Asmussen
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | | | - Katrin Dulitz
- Institute of Physics, University of Freiburg, Germany
| | - Aaron Ngai
- Institute of Physics, University of Freiburg, Germany
| | | | - Manuel Barranco
- Departament FQA, Facultat de Física, Universitat de Barcelona, Spain and Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | - Marcel Binz
- Institute of Physics, University of Freiburg, Germany
| | - Lukas Bruder
- Institute of Physics, University of Freiburg, Germany
| | | | | | - Jussi Eloranta
- Department of Chemistry and Biochemistry, California State University at Northridge, Northridge, CA 91330, USA
| | | | - Luca Giannessi
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | - Marti Pi
- Departament FQA, Facultat de Física, Universitat de Barcelona, Spain and Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | - Oksana Plekan
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | - Kevin C Prince
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | | | - Daniel Uhl
- Institute of Physics, University of Freiburg, Germany
| | | | - Marco Zangrando
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain and CNR-IOM, Elettra-Sincrotrone Trieste S.C.p.A., Italy
| | - Carlo Callegari
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | | | - Marcel Mudrich
- Department of Physics and Astronomy, Aarhus University, Denmark.
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11
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Observation of laser-assisted electron scattering in superfluid helium. Nat Commun 2021; 12:4204. [PMID: 34244517 PMCID: PMC8270992 DOI: 10.1038/s41467-021-24479-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 06/18/2021] [Indexed: 11/08/2022] Open
Abstract
Laser-assisted electron scattering (LAES), a light-matter interaction process that facilitates energy transfer between strong light fields and free electrons, has so far been observed only in gas phase. Here we report on the observation of LAES at condensed phase particle densities, for which we create nano-structured systems consisting of a single atom or molecule surrounded by a superfluid He shell of variable thickness (32-340 Å). We observe that free electrons, generated by femtosecond strong-field ionization of the core particle, can gain several tens of photon energies due to multiple LAES processes within the liquid He shell. Supported by Monte Carlo 3D LAES and elastic scattering simulations, these results provide the first insight into the interplay of LAES energy gain/loss and dissipative electron movement in a liquid. Condensed-phase LAES creates new possibilities for space-time studies of solids and for real-time tracing of free electrons in liquids.
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12
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Abstract
AbstractWe have measured depletion spectra of the heteronuclear (85Rb87Rb+) dimer cation complexed with up to 10 He atoms. Two absorption bands are observed between 920 and 250 nm. The transition into the repulsive 12Σu+state of HeRb2+gives rise to a broad feature at 790 nm (12,650 cm−1); it exhibits a blueshift of 98 cm−1per added He atom. The transition into the bound 12Πustate of HeRb2+reveals vibrational structure with a band head at ≤ 15,522 cm−1, a harmonic constant of 26 cm−1, and a spin–orbit splitting of ≤ 183 cm−1. The band experiences an average redshift of − 38 cm−1per added He atom. Ab initio calculations rationalize the shape of the spectra and spectral shifts with respect to the number of helium atoms attached. For a higher number of solvating helium atoms, symmetric solvation on both ends of the Rb2+ion is predicted.
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13
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Ernst WE, Hauser AW. Metal clusters synthesized in helium droplets: structure and dynamics from experiment and theory. Phys Chem Chem Phys 2020; 23:7553-7574. [PMID: 33057510 DOI: 10.1039/d0cp04349d] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Metal clusters have drawn continuous interest because of their high potential for the assembly of matter with special properties that may significantly differ from the corresponding bulk. Controlled combination of particular elements in one nanoparticle can increase the options for the creation of new materials for photonic, catalytic, or electronic applications. Superfluid helium droplets provide confinement and ultralow temperature, i.e. an ideal environment for the atom-by-atom aggregation of a new nanoparticle. This perspective presents a review of the current research progress on the synthesis of tailored metal and metal oxide clusters including core-shell designs, their characterization within the helium droplet beam, deposition on various solid substrates, and analysis via surface diagnostics. Special attention is given to the thermal properties of mixed metal clusters and questions about alloy formation on the nanoscale. Experimental results are accompanied by theoretical approaches employing computational chemistry, molecular dynamics simulations and He density functional theory.
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Affiliation(s)
- Wolfgang E Ernst
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria.
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14
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González-Lezana T, Echt O, Gatchell M, Bartolomei M, Campos-Martínez J, Scheier P. Solvation of ions in helium. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1794585] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Tomás González-Lezana
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
- Department of Physics, University of New Hampshire, Durham, NH, USA
| | - Michael Gatchell
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - Massimiliano Bartolomei
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - José Campos-Martínez
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
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15
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Thaler B, Meyer M, Heim P, Koch M. Long-Lived Nuclear Coherences inside Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2020; 124:115301. [PMID: 32242724 DOI: 10.1103/physrevlett.124.115301] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 02/06/2020] [Indexed: 05/20/2023]
Abstract
Much of our knowledge about dynamics and functionality of molecular systems has been achieved with femtosecond time-resolved spectroscopy. Despite extensive technical developments over the past decades, some classes of systems have eluded dynamical studies so far. Here, we demonstrate that superfluid helium nanodroplets, acting as a thermal bath of 0.4 K temperature to stabilize weakly bound or reactive systems, are well suited for time-resolved studies of single molecules solvated in the droplet interior. By observing vibrational wave packet motion of indium dimers (In_{2}) for tens of picoseconds, we demonstrate that the perturbation imposed by this quantum liquid can be lower by a factor of 10-100 compared to any other solvent, which uniquely allows us to study processes depending on long nuclear coherence in a dissipative environment. Furthermore, tailor-made microsolvation environments inside droplets will enable us to investigate the solvent influence on intramolecular dynamics in a wide tuning range from molecular isolation to strong molecule-solvent coupling.
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Affiliation(s)
- Bernhard Thaler
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria
| | - Miriam Meyer
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria
| | - Pascal Heim
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria
| | - Markus Koch
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria
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16
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Mudrich M, LaForge AC, Ciavardini A, O'Keeffe P, Callegari C, Coreno M, Demidovich A, Devetta M, Fraia MD, Drabbels M, Finetti P, Gessner O, Grazioli C, Hernando A, Neumark DM, Ovcharenko Y, Piseri P, Plekan O, Prince KC, Richter R, Ziemkiewicz MP, Möller T, Eloranta J, Pi M, Barranco M, Stienkemeier F. Ultrafast relaxation of photoexcited superfluid He nanodroplets. Nat Commun 2020; 11:112. [PMID: 31913265 PMCID: PMC6949273 DOI: 10.1038/s41467-019-13681-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 11/19/2019] [Indexed: 11/23/2022] Open
Abstract
The relaxation of photoexcited nanosystems is a fundamental process of light–matter interaction. Depending on the couplings of the internal degrees of freedom, relaxation can be ultrafast, converting electronic energy in a few fs, or slow, if the energy is trapped in a metastable state that decouples from its environment. Here, we study helium nanodroplets excited resonantly by femtosecond extreme-ultraviolet (XUV) pulses from a seeded free-electron laser. Despite their superfluid nature, we find that helium nanodroplets in the lowest electronically excited states undergo ultrafast relaxation. By comparing experimental photoelectron spectra with time-dependent density functional theory simulations, we unravel the full relaxation pathway: Following an ultrafast interband transition, a void nanometer-sized bubble forms around the localized excitation (He\documentclass[12pt]{minimal}
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\begin{document}$${}^{* }$$\end{document}*) within 1 ps. Subsequently, the bubble collapses and releases metastable He\documentclass[12pt]{minimal}
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\begin{document}$${}^{* }$$\end{document}* at the droplet surface. This study highlights the high level of detail achievable in probing the photodynamics of nanosystems using tunable XUV pulses. There is interest in understanding the relaxation mechanisms of photoexcitation in atoms, molecules and other complex systems. Here the authors unravel the photoexcitation and ultrafast relaxation of superfluid helium nanodroplets using a pump-probe experiment with FEL pulses.
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Affiliation(s)
- M Mudrich
- Department of Physics and Astronomy, Aarhus University, Aarhus C, 8000, Denmark.
| | - A C LaForge
- Institute of Physics, University of Freiburg, Freiburg im Breisgau, 79104, Germany.,Department of Physics, University of Connecticut, Storrs, CT, 06269, USA
| | - A Ciavardini
- CNR-ISM, Area della Ricerca di Roma 1, Monterotondo Scalo, 00015, Italy.,CERIC-ERIC Basovizza, Trieste, 34149, Italy
| | - P O'Keeffe
- CNR-ISM, Area della Ricerca di Roma 1, Monterotondo Scalo, 00015, Italy
| | - C Callegari
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste, 34149, Italy
| | - M Coreno
- CNR-ISM, Area della Ricerca di Roma 1, Monterotondo Scalo, 00015, Italy
| | - A Demidovich
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste, 34149, Italy
| | - M Devetta
- Dipartimento di Fisica, Università degli Studi di Milano, Milan, 20133, Italy.,CNR-IFN, Milano, 20133, Italy
| | - M Di Fraia
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste, 34149, Italy
| | - M Drabbels
- Laboratory of Molecular Nanodynamics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015, Switzerland
| | - P Finetti
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste, 34149, Italy
| | - O Gessner
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - C Grazioli
- CNR-IOM, Istituto Officina dei Materiali, Area Science Park - Basovizza, Trieste, 34149, Italy
| | - A Hernando
- Kido Dynamics, EPFL Innovation Park Bat. C, 1015, Lausanne, Switzerland.,IFISC (CSIC-UIB), Instituto de Fisica Interdisciplinar y Sistemas Complejos, Campus Universitat de les Illes Balears, 07122, Palma de Mallorca, Spain
| | - D M Neumark
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Y Ovcharenko
- Institut für Optik und Atomare Physik, TU-Berlin, 10623, Germany.,European XFEL, Schenefeld, 22869, Germany
| | - P Piseri
- Dipartimento di Fisica, Università degli Studi di Milano, Milan, 20133, Italy
| | - O Plekan
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste, 34149, Italy
| | - K C Prince
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste, 34149, Italy
| | - R Richter
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste, 34149, Italy
| | - M P Ziemkiewicz
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - T Möller
- Institut für Optik und Atomare Physik, TU-Berlin, 10623, Germany
| | - J Eloranta
- Department of Chemistry and Biochemistry, California State University at Northridge, Northridge, CA, 91330, USA
| | - M Pi
- Departament FQA, Facultat de Física, Universitat de Barcelona, Barcelona, 08028, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, 08028, Spain
| | - M Barranco
- Departament FQA, Facultat de Física, Universitat de Barcelona, Barcelona, 08028, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, 08028, Spain.,Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, Toulouse, Cedex 09, 31062, France
| | - F Stienkemeier
- Institute of Physics, University of Freiburg, Freiburg im Breisgau, 79104, Germany
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17
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Thaler B, Heim P, Treiber L, Koch M. Ultrafast photoinduced dynamics of single atoms solvated inside helium nanodroplets. J Chem Phys 2020; 152:014307. [PMID: 31914752 DOI: 10.1063/1.5130145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Helium nanodroplets can serve as reaction containers for photoinduced time-resolved studies of cold, isolated molecular systems that are otherwise inaccessible. Recently, three different dynamical processes, triggered by photoexcitation of a single atom inside a droplet, were observed in their natural time scale: Expansion of the He solvation shell (He bubble) within 600 fs initiates a collective bubble oscillation with a ∼30 ps oscillation period, followed by dopant ejection after ∼60 ps. Here, we present a systematic investigation of these processes by combining time-resolved photoelectron and photoion spectroscopy with time-dependent He density functional theory simulations. By variation of the photoexcitation energy, we find that the full excess excitation energy, represented by the blue-shifted in-droplet excitation band, is completely transferred to the He environment during the bubble expansion. Surprisingly, we find that variation of the droplet size has only a minor influence on the ejection time, providing insight into the spatial distribution of the ground-state atoms before photoexcitation. Simulated particle trajectories after photoexcitation are in agreement with experimental observations and suggest that the majority of ground-state atoms are located at around 16 Å below the droplet surface. Bubble expansion and oscillation are purely local effects, depending only on the ultimate dopant environment. These solvation-induced dynamics will be superimposed on intramolecular dynamics of molecular systems, and a mechanistic description is fundamental for the interpretation of future experiments.
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Affiliation(s)
- Bernhard Thaler
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria
| | - Pascal Heim
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria
| | - Leonhard Treiber
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria
| | - Markus Koch
- Graz University of Technology, Institute of Experimental Physics, Petersgasse 16, 8010 Graz, Austria
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18
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Blancafort-Jorquera M, Vilà A, González M. Quantum-classical approach to the reaction dynamics in a superfluid helium nanodroplet. The Ne 2 dimer and Ne-Ne adduct formation reaction Ne + Ne-doped nanodroplet. Phys Chem Chem Phys 2019; 21:24218-24231. [PMID: 31661098 DOI: 10.1039/c9cp04561a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dynamics of the Ne2 dimer and Ne-Ne adduct formation in a superfluid helium nanodroplet [(4He)N; T = 0.37 K], Ne + Ne@(4He)N→ Ne2@(4He)N'/Ne-Ne@(4He)N' + (N-N')4He with N = 500, has been investigated using a hybrid approach (quantum and classical mechanics (QM-CM) descriptions for helium and the Ne atoms, respectively) and taking into account the angular momentum of the attacking Ne atom, Ne(1). Comparison with zero angular momentum QM results of our own shows that the present results are similar to the quantum ones for the initial Ne(1) velocities (v0) of 500 and 800 m s-1 (the former one being the most probable velocity of Ne at 300 K), in all cases leading to the Ne2 dimer (re = 3.09 Å). However, significant differences appear below v0 = 500 m s-1, because in the QM-CM dynamics, instead of the dimer, a Ne-Ne adduct is formed (r0 = 5.45 Å). The formation of this adduct will probably dominate as the contribution to reactivity of angular momenta larger than zero is the leading one and angular momentum strongly acts against the Ne2 production. Angular momentum adds further difficulties in producing the dimer, since it makes it more difficult to remove the helium density between both Ne atoms to lead, subsequently, to the Ne2 molecule. Hence, the formation of the neon-neon adduct, Ne-Ne@(4He)N', clearly dominates the reactivity of the system, which results in the formation of a "quantum gel"/"quantum foam", because the two Ne atoms essentially maintain their identity inside the nanodroplet. Large enough Ne(1) initial angular momentum values can induce the formation of vortex lines by the collapse of superficial excitations (ripplons), but they occur with greater difficulty than in the case of the capture of the Ne atom by a non doped helium nanodroplet, due to the wave interferences induced by the Ne induced by the solvation layers of the Ne atom originally placed inside the nanodroplet. We hope that this work will encourage other researchers to investigate the reaction dynamics in helium nanodroplets, an interesting topic on which there are few studies available.
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Affiliation(s)
- Miquel Blancafort-Jorquera
- Departament de Ciència de Materials i Química Física and IQTC, Universitat de Barcelona, Martí i Franquès, 1-11, 08028 Barcelona, Spain.
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19
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Alghamdi M, Zhang J, Kong W. Doping with multiple cations and failure of charge transfer in large ionized helium droplets. J Chem Phys 2019; 151:134307. [PMID: 31594345 DOI: 10.1063/1.5123735] [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
We report experimental observations of aniline (A) cations and He2 + when aniline is doped into ionized helium droplets. Large droplets containing 108 atoms are bombarded by energetic electrons, resulting in more than one positive charge in one droplet. When aniline encounters the charged droplets, some are ionized via charge transfer, while others can remain neutral in the presence of He2 + when the mass-to-charge ratio (m/z) of the droplet is sufficiently large. Upon resonant excitation of the dopant An or An + (n ≥ 1), He2 + can be ejected. The excitation spectrum of He2 + becomes a juxtaposition of the spectra of An and An +. Moreover, an anticorrelation between the yields of He2 + and A+ is observed with increasing energies of the ionizing electrons. We attribute this result to the combined effect of reduction in m/z of the droplets and the different locations of He2 + and neutral An. Limited by the penetration depths of the ionizing electrons and further assisted by the Coulomb repulsion of coexisting cations, He2 + is located within 20 nm of the surface, while neutral An has an average position inside a large droplet. Upon resonant excitation of the interior An, He2 + is preferentially ejected. With increasing energies of the colliding electrons, the m/z of the droplets are reduced, leading to less effective charge shielding and more effective charge transfer, until ultimately, all He2 + can be neutralized to form A+.
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Affiliation(s)
- Maha Alghamdi
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA
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20
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Thaler B, Meyer R, Heim P, Ranftl S, Pototschnig JV, Hauser AW, Koch M, Ernst WE. Conservation of Hot Thermal Spin-Orbit Population of 2P Atoms in a Cold Quantum Fluid Environment. J Phys Chem A 2019; 123:3977-3984. [PMID: 30973728 DOI: 10.1021/acs.jpca.9b02920] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 0.4 K internal temperature of superfluid helium nanodroplets is believed to guarantee a corresponding ground-state population of dopant atoms and molecules inside this cryogenic matrix. We have recorded 6s ← 5p excitation spectra of indium atoms in helium droplets and found two absorption bands separated by about 2000 cm-1, a value close to the spin-orbit (SO) splitting of the In 2P ground state. The intensities of the bands agree with a thermal population of the 2P1/2 and 2P3/2 states at 870 K, the temperature of the In pick-up cell. Applying femtosecond pump-probe spectroscopy, we found the same dynamical response of the helium solvation shell after the photoexcitation of the two bands. He-density functional theory simulations of the excitation spectra are in agreement with the bimodal structure. Our findings show that the population of SO levels of hot dopants is conserved after pick-up inside the superfluid droplet. Implications for the interpretation of experiments on molecular aggregates are discussed.
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Affiliation(s)
- Bernhard Thaler
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , 8010 Graz , Austria
| | - Ralf Meyer
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , 8010 Graz , Austria
| | - Pascal Heim
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , 8010 Graz , Austria
| | - Sascha Ranftl
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , 8010 Graz , Austria
| | - Johann V Pototschnig
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , 8010 Graz , Austria
| | - Andreas W Hauser
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , 8010 Graz , Austria
| | - Markus Koch
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , 8010 Graz , Austria
| | - Wolfgang E Ernst
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , 8010 Graz , Austria
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