1
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Rendler N, Scognamiglio A, Barranco M, Pí M, Halberstadt N, Dulitz K, Stienkemeier F. Dynamics of Photoexcited Cs Atoms Attached to Helium Nanodroplets. J Phys Chem A 2021; 125:9048-9059. [PMID: 34619968 DOI: 10.1021/acs.jpca.1c05467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present an experimental study of the dynamics following the photoexcitation and subsequent photoionization of single Cs atoms on the surface of helium nanodroplets. The dynamics of excited Cs atom desorption and readsorption as well as CsHe exciplex formation are measured by using femtosecond pump-probe velocity map imaging spectroscopy and ion time-of-flight spectrometry. The time scales for the desorption of excited Cs atoms off helium nanodroplets as well as the time scales for CsHe exciplex formation are experimentally determined for the 6p states of Cs. For the 6p 2Π1/2 state, our results confirm that the excited Cs atoms only desorb from the nanodroplet when the excitation wavenumber is blue-shifted from the 6p 2Π1/2 ← 6s 2Σ1/2 resonance. Our results suggest that the dynamics following excitation to the 6p 2Π3/2 state can be described by an evaporation-like desorption mechanism, whereas the dynamics arising from excitation to the 6p 2Σ1/2 state is indicative for a more impulsive desorption process. Furthermore, our results suggest a helium-induced spin-orbit relaxation from the 6p 2Σ1/2 state to the 6p 2Π1/2 state. Our findings largely agree with the results of time-dependent 4He density functional theory (DFT) simulations published earlier [Eur. Phys. J. D 2019, 73, 94].
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Affiliation(s)
- Nicolas Rendler
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Audrey Scognamiglio
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Manuel Barranco
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, Université de Toulouse, CNRS UMR 5589, 118 route de Narbonne, 31062 Toulouse Cedex 09, France.,Departament FQA, Facultat de Física, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Marti Pí
- Departament FQA, Facultat de Física, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Nadine Halberstadt
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, Université de Toulouse, CNRS UMR 5589, 118 route de Narbonne, 31062 Toulouse Cedex 09, France
| | - Katrin Dulitz
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Frank Stienkemeier
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
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2
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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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3
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Ben Ltaief L, Shcherbinin M, Mandal S, Krishnan SR, Richter R, Pfeifer T, Bauer M, Ghosh A, Mudrich M, Gokhberg K, LaForge AC. Electron transfer mediated decay of alkali dimers attached to He nanodroplets. Phys Chem Chem Phys 2020; 22:8557-8564. [DOI: 10.1039/d0cp00256a] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Double ionization of alkali dimers attached to He nanodroplets by electron transfer mediated decay (ETMD).
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Affiliation(s)
- L. Ben Ltaief
- Department of Physics and Astronomy
- Aarhus University
- 8000 Aarhus C
- Denmark
| | - M. Shcherbinin
- Department of Physics and Astronomy
- Aarhus University
- 8000 Aarhus C
- Denmark
| | - S. Mandal
- Indian Institute of Science Education and Research
- Pune 411008
- India
| | - S. R. Krishnan
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - R. Richter
- Elettra-Sincrotrone Trieste
- 34149 Basovizza
- Italy
| | - T. Pfeifer
- Max-Planck-Institut für Kernphysik
- 69117 Heidelberg
- Germany
| | - M. Bauer
- Physikalisch-Chemisches Institut
- Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - A. Ghosh
- Physikalisch-Chemisches Institut
- Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - M. Mudrich
- Department of Physics and Astronomy
- Aarhus University
- 8000 Aarhus C
- Denmark
- Indian Institute of Technology Madras
| | - K. Gokhberg
- Physikalisch-Chemisches Institut
- Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - A. C. LaForge
- Department of Physics
- University of Connecticut
- Storrs
- USA
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4
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Ben Ltaief L, Shcherbinin M, Mandal S, Krishnan SR, LaForge AC, Richter R, Turchini S, Zema N, Pfeifer T, Fasshauer E, Sisourat N, Mudrich M. Charge Exchange Dominates Long-Range Interatomic Coulombic Decay of Excited Metal-Doped Helium Nanodroplets. J Phys Chem Lett 2019; 10:6904-6909. [PMID: 31625747 DOI: 10.1021/acs.jpclett.9b02726] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Atoms and molecules attached to rare-gas clusters are ionized by an interatomic autoionization process traditionally termed "Penning ionization" when the host cluster is resonantly excited. Here we analyze this process in the light of the interatomic Coulombic decay (ICD) mechanism, which usually contains a contribution from charge exchange at a short interatomic distance and one from virtual photon transfer at a large interatomic distance. For helium (He) nanodroplets doped with alkali metal atoms (Li, Rb), we show that long-range and short-range contributions to the interatomic autoionization can be clearly distinguished by detecting electrons and ions in coincidence. Surprisingly, ab initio calculations show that even for alkali metal atoms floating in dimples at a large distance from the nanodroplet surface, autoionization is largely dominated by charge-exchange ICD. Furthermore, the measured electron spectra manifest the ultrafast internal relaxation of the droplet mainly into the 1s2s1S state and partially into the metastable 1s2s3S state.
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Affiliation(s)
- L Ben Ltaief
- Department of Physics and Astronomy , Aarhus University , 8000 Aarhus C , Denmark
| | - M Shcherbinin
- Department of Physics and Astronomy , Aarhus University , 8000 Aarhus C , Denmark
| | - S Mandal
- Indian Institute of Science Education and Research , Pune 411008 , India
| | - S R Krishnan
- Department of Physics , Indian Institute of Technology , Madras, Chennai 600 036 , India
| | - A C LaForge
- Department of Physics , University of Connecticut , Storrs , Connecticut 06269 , United States
| | - R Richter
- Elettra-Sincrotrone Trieste , Basovizza, 34149 Trieste , Italy
| | - S Turchini
- Istituto Struttura della Materia-CNR (ISM-CNR) , 00133 Roma , Italy
| | - N Zema
- Istituto Struttura della Materia-CNR (ISM-CNR) , 00133 Roma , Italy
| | - T Pfeifer
- Max-Planck-Institut für Kernphysik , 69117 Heidelberg , Germany
| | - E Fasshauer
- Department of Physics and Astronomy , Aarhus University , 8000 Aarhus C , Denmark
| | - N Sisourat
- Sorbonne Université, CNRS , Laboratoire de Chimie Physique Matière et Rayonnement, UMR 7614 , F-75005 Paris , France
| | - M Mudrich
- Department of Physics and Astronomy , Aarhus University , 8000 Aarhus C , Denmark
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5
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Abstract
We report suppression of multiphoton ionization (MPI) of aniline doped large superfluid helium droplets containing over 5 × 106 atoms. In contrast, surface-bound sodium atoms and dimers are readily desorbed and ionized. Adequacy of the experimental conditions is also confirmed from ejection of embedded aniline cations from smaller droplets containing multiple cations, and MPI of gaseous aniline. The photoelectrons have a mean-free-path of less than 1 nm and a thermalization distance of 10 nm. In a droplet with a diameter of over 70 nm, effective charge recombination within the droplet is expected.
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6
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Martinez M, Coppens F, Barranco M, Halberstadt N, Pi M. 4s to 5s and 4p photoexcitation dynamics of K atoms from the surface of helium nanodroplets: a theoretical study. Phys Chem Chem Phys 2019; 21:3626-3636. [DOI: 10.1039/c8cp05253k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the photodissociation of the potassium atom from a superfluid helium nanodroplet upon 5s 2S or 4p 2P excitation using the time-dependent helium density functional method (He-TDDFT). The results show possible K spin–orbit relaxation.
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Affiliation(s)
- Maxime Martinez
- Laboratoire Collisions Agrégats Réactivité (LCAR)
- IRSAMC
- Université de Toulouse
- CNRS UMR 5589
- Toulouse
| | - François Coppens
- Laboratoire Collisions Agrégats Réactivité (LCAR)
- IRSAMC
- Université de Toulouse
- CNRS UMR 5589
- Toulouse
| | - Manuel Barranco
- Laboratoire Collisions Agrégats Réactivité (LCAR)
- IRSAMC
- Université de Toulouse
- CNRS UMR 5589
- Toulouse
| | - Nadine Halberstadt
- Laboratoire Collisions Agrégats Réactivité (LCAR)
- IRSAMC
- Université de Toulouse
- CNRS UMR 5589
- Toulouse
| | - Martí Pi
- Departament FQA
- Facultat de Física
- Universitat de Barcelona. Diagonal 645
- 08028 Barcelona
- Spain
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7
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Coppens F, Ancilotto F, Barranco M, Halberstadt N, Pi M. Dynamics of impurity clustering in superfluid 4He nanodroplets. Phys Chem Chem Phys 2019; 21:17423-17432. [DOI: 10.1039/c9cp02789k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Snapshot taken at 75 ps of the capture of six Ar atoms hitting a 4He5000 droplet at 100 m s−1.
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Affiliation(s)
- François Coppens
- Université Toulouse 3 and CNRS
- Laboratoire des Collisions
- Agrégats et Réactivité
- IRSAMC
- F-31062 Toulouse Cedex 09
| | - Francesco Ancilotto
- Dipartimento di Fisica e Astronomia “Galileo Galilei” and CNISM
- Università di Padova
- 35122 Padova
- Italy
- CNR-IOM Democritos
| | - Manuel Barranco
- Université Toulouse 3 and CNRS
- Laboratoire des Collisions
- Agrégats et Réactivité
- IRSAMC
- F-31062 Toulouse Cedex 09
| | - Nadine Halberstadt
- Université Toulouse 3 and CNRS
- Laboratoire des Collisions
- Agrégats et Réactivité
- IRSAMC
- F-31062 Toulouse Cedex 09
| | - Martí Pi
- Departament FQA
- Facultat de Física
- Universitat de Barcelona
- 08028 Barcelona
- Spain
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8
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Lackner F, Krois G, Ernst WE. Lithium atoms on helium nanodroplets: Rydberg series and ionization dynamics. J Chem Phys 2018; 147:184302. [PMID: 29141430 DOI: 10.1063/1.5004543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The electronic excitation spectrum of lithium atoms residing on the surface of helium nanodroplets is presented and analyzed employing a Rydberg-Ritz approach. Utilizing resonant two-photon ionization spectroscopy, two different Rydberg series have been identified: one assigned to the nS(Σ) series and the other with predominantly nP(Π) character. For high Rydberg states, which have been resolved up to n = 13, the surrounding helium effectively screens the valence electron from the Li ion core, as indicated by the apparent red-shift of Li transitions and lowered quantum defects on the droplet with respect to their free atom counterparts. For low n states, the screening effect is weakened and the prevailing repulsive interaction gives rise to strongly broadened and blue-shifted transitions. The red-shifts originate from the polarization of nearby He atoms by the positive Li ion core. As a consequence of this effect, the ionization threshold is lowered by 116 ± 10 cm-1 for Li on helium droplets with a radius of about 40 Å. Upon single-photon ionization, heavy complexes corresponding to Li ions attached to intact helium droplets are detected. We conclude that ionization close to the on-droplet ionization threshold triggers a dynamic process in which the Li ion core undergoes a transition from a surface site into the droplet.
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Affiliation(s)
- Florian Lackner
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Günter Krois
- 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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9
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Vindel Zandbergen P, Barranco M, Cargnoni F, Drabbels M, Pi M, Halberstadt N. Helium-induced electronic transitions in photo-excited Ba+–Hen exciplexes. J Chem Phys 2018; 148:144302. [DOI: 10.1063/1.5022863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Patricia Vindel Zandbergen
- Laboratoire Collisions Agrégats Réactivité (LCAR), IRSAMC, Université de Toulouse, CNRS UMR 5589, Toulouse, France
| | - Manuel Barranco
- Laboratoire Collisions Agrégats Réactivité (LCAR), IRSAMC, Université de Toulouse, CNRS UMR 5589, Toulouse, France
- Departament FQA, Facultat de Física, Universitat de Barcelona, Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain
| | | | - Marcel Drabbels
- Laboratory of Molecular Nanodynamics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Martí Pi
- Departament FQA, Facultat de Física, Universitat de Barcelona, Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain
| | - Nadine Halberstadt
- Laboratoire Collisions Agrégats Réactivité (LCAR), IRSAMC, Université de Toulouse, CNRS UMR 5589, Toulouse, France
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10
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Ancilotto F, Levy D, Pimentel J, Eloranta J. First Observation of Bright Solitons in Bulk Superfluid ^{4}He. PHYSICAL REVIEW LETTERS 2018; 120:035302. [PMID: 29400543 DOI: 10.1103/physrevlett.120.035302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 09/21/2017] [Indexed: 06/07/2023]
Abstract
The existence of bright solitons in bulk superfluid ^{4}He is demonstrated by time-resolved shadowgraph imaging experiments and density functional theory (DFT) calculations. The initial liquid compression that leads to the creation of nonlinear waves is produced by rapidly expanding plasma from laser ablation. After the leading dissipative period, these waves transform into bright solitons, which exhibit three characteristic features: dispersionless propagation, negligible interaction in a two-wave collision, and direct dependence between soliton amplitude and the propagation velocity. The experimental observations are supported by DFT calculations, which show rapid evolution of the initially compressed liquid into bright solitons. At high amplitudes, solitons become unstable and break down into dispersive shock waves.
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Affiliation(s)
- Francesco Ancilotto
- Dipartimento di Fisica e Astronomia "Galileo Galilei" and CNISM, Università di Padova, via Marzolo 8, 35122 Padova, Italy and CNR-IOM Democritos, via Bonomea, 265-34136 Trieste, Italy
| | - David Levy
- Department of Physics and Astronomy, California State University, Northridge, Northridge, California 91330, USA
| | - Jessica Pimentel
- Department of Chemistry and Biochemistry, California State University, Northridge, Northridge, California 91330, USA
| | - Jussi Eloranta
- Department of Chemistry and Biochemistry, California State University, Northridge, Northridge, California 91330, USA
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11
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Coppens F, von Vangerow J, Barranco M, Halberstadt N, Stienkemeier F, Pi M, Mudrich M. Desorption dynamics of RbHe exciplexes off He nanodroplets induced by spin-relaxation. Phys Chem Chem Phys 2018; 20:9309-9320. [DOI: 10.1039/c8cp00482j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Doped He nanodroplets are ideal model systems to study elementary photophysical processes in hetero-nanostructures. Here we study the formation of free RbHe exciplexes from laser-excited Rb-doped He nanodroplets.
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Affiliation(s)
- François Coppens
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, Université Toulouse 3- Paul Sabatier, CNRS UMR 5589
- F-31062 Toulouse Cedex 09
- France
| | | | - Manuel Barranco
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, Université Toulouse 3- Paul Sabatier, CNRS UMR 5589
- F-31062 Toulouse Cedex 09
- France
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona
- 08028 Barcelona
| | - Nadine Halberstadt
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, Université Toulouse 3- Paul Sabatier, CNRS UMR 5589
- F-31062 Toulouse Cedex 09
- France
| | | | - Martí Pi
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona
- 08028 Barcelona
- Spain
- Departament FQA, Facultat de Física, Universitat de Barcelona
- 08028 Barcelona
| | - Marcel Mudrich
- Department of Physics and Astronomy, Aarhus University
- Aarhus 8000 C
- Denmark
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12
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Ancilotto F, Barranco M, Coppens F, Eloranta J, Halberstadt N, Hernando A, Mateo D, Pi M. Density functional theory of doped superfluid liquid helium and nanodroplets. INT REV PHYS CHEM 2017. [DOI: 10.1080/0144235x.2017.1351672] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Francesco Ancilotto
- Dipartimento di Fisica e Astronomia ‘Galileo Galilei’ and CNISM, Università di Padova, Padova, Italy
- CNR-IOM Democritos, Trieste, Italy
| | - Manuel Barranco
- Facultat de Física, Departament FQA, Universitat de Barcelona, Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain
- Laboratoire des Collisions, Agrégats et Réactivité, IRSAMC, Université Toulouse 3 and CNRS, Toulouse Cedex 09, France
| | - François Coppens
- Laboratoire des Collisions, Agrégats et Réactivité, IRSAMC, Université Toulouse 3 and CNRS, Toulouse Cedex 09, France
| | - Jussi Eloranta
- Department of Chemistry and Biochemistry, California State University at Northridge, Northridge, CA, USA
| | - Nadine Halberstadt
- Laboratoire des Collisions, Agrégats et Réactivité, IRSAMC, Université Toulouse 3 and CNRS, Toulouse Cedex 09, France
| | - Alberto Hernando
- Social Thermodynamics Applied Research (SThAR), EPFL Innovation Park, Lausanne, Switzerland
| | - David Mateo
- Applied Complexity Group, Singapore University of Technology and Design, Singapore, Singapore
| | - Martí Pi
- Facultat de Física, Departament FQA, Universitat de Barcelona, Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain
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13
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von Vangerow J, Coppens F, Leal A, Pi M, Barranco M, Halberstadt N, Stienkemeier F, Mudrich M. Imaging Excited-State Dynamics of Doped He Nanodroplets in Real-Time. J Phys Chem Lett 2017; 8:307-312. [PMID: 27996261 DOI: 10.1021/acs.jpclett.6b02598] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The real-time dynamics of excited alkali metal atoms (Rb) attached to quantum fluid He nanodroplets is investigated using femtosecond imaging spectroscopy and time-dependent density functional theory. We disentangle the competing dynamics of desorption of excited Rb atoms off the He droplet surface and solvation inside the droplet interior as the Rb atom is ionized. For Rb excited to the 5p and 6p states, desorption occurs on starkly differing time scales (∼100 versus ∼1 ps, respectively). The comparison between theory and experiment indicates that desorption proceeds either impulsively (6p) or in a transition regime between impulsive dissociation and complex desorption (5p).
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Affiliation(s)
- Johannes von Vangerow
- Physikalisches Institut, Universität Freiburg , Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - François Coppens
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09, France
| | - Antonio Leal
- Departament FQA, Facultat de Física, and IN2UB, Universitat de Barcelona , Diagonal 645, 08028 Barcelona, Spain
| | - Martí Pi
- Departament FQA, Facultat de Física, and IN2UB, Universitat de Barcelona , Diagonal 645, 08028 Barcelona, Spain
| | - Manuel Barranco
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09, France
- Departament FQA, Facultat de Física, and IN2UB, Universitat de Barcelona , Diagonal 645, 08028 Barcelona, Spain
| | - Nadine Halberstadt
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09, France
| | - Frank Stienkemeier
- Physikalisches Institut, Universität Freiburg , Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Marcel Mudrich
- Physikalisches Institut, Universität Freiburg , Hermann-Herder-Str. 3, 79104 Freiburg, Germany
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14
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Seki Y, Takayanagi T, Shiga M. Photoexcited Ag ejection from a low-temperature He cluster: a simulation study by nonadiabatic Ehrenfest ring-polymer molecular dynamics. Phys Chem Chem Phys 2017; 19:13798-13806. [DOI: 10.1039/c7cp00888k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nonadiabatic ring-polymer molecular dynamics simulations were performed to understand the photoexcitation dynamics of a low-temperature Ag·He500 cluster.
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Affiliation(s)
- Yusuke Seki
- Department of Chemistry
- Saitama University
- Saitama City
- Japan
| | | | - Motoyuki Shiga
- Center for Computational Science and E-Systems
- Japan Atomic Energy Agency
- Kashiwa
- Japan
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15
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Coppens F, Ancilotto F, Barranco M, Halberstadt N, Pi M. Capture of Xe and Ar atoms by quantized vortices in4He nanodroplets. Phys Chem Chem Phys 2017; 19:24805-24818. [DOI: 10.1039/c7cp03307a] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a computational study, based on time-dependent Density Functional theory, of the real-time interaction and trapping of Ar and Xe atoms in superfluid4He nanodroplets either pure or hosting quantized vortex lines.
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Affiliation(s)
- François Coppens
- Université de Toulouse
- UPS
- Laboratoire Collisions Agrégats Réactivité
- IRSAMC
- F-31062 Toulouse
| | - Francesco Ancilotto
- Dipartimento di Fisica e Astronomia ‘Galileo Galilei’ and CNISM
- Università di Padova
- 35122 Padova
- Italy
- CNR-IOM Democritos
| | - Manuel Barranco
- Université de Toulouse
- UPS
- Laboratoire Collisions Agrégats Réactivité
- IRSAMC
- F-31062 Toulouse
| | - Nadine Halberstadt
- Université de Toulouse
- UPS
- Laboratoire Collisions Agrégats Réactivité
- IRSAMC
- F-31062 Toulouse
| | - Martí Pi
- Facultat de Física
- Departament FQA
- Universitat de Barcelona
- 08028 Barcelona
- Spain
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16
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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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17
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Leal A, Zhang X, Barranco M, Cargnoni F, Hernando A, Mateo D, Mella M, Drabbels M, Pi M. Dynamics of photoexcited Ba(+) cations in (4)He nanodroplets. J Chem Phys 2016; 144:094302. [PMID: 26957164 DOI: 10.1063/1.4942850] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We present a joint experimental and theoretical study on the desolvation of Ba(+) cations in (4)He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba(+) cations and Ba(+)Hen exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba(+) Hen exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba(+). In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba(+) cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba(+) cations or exciplexes, even when relaxation pathways to lower lying states are included.
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Affiliation(s)
- Antonio Leal
- Departament ECM, Facultat de Física, and INUB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Xiaohang Zhang
- Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Manuel Barranco
- Departament ECM, Facultat de Física, and INUB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Fausto Cargnoni
- Istituto di Scienze e Tecnologie Molecolari (ISTM), Consiglio Nazionale delle Ricerche, via Golgi 19, 20133 Milano, Italy
| | - Alberto Hernando
- Social Thermodynamics Applied Research (SThAR), EPFL Innovation Park, Bâtiment C, CH-1015 Lausanne, Switzerland
| | - David Mateo
- Department of Chemistry and Biochemistry, California State University at Northridge, Northridge, California 91330, USA
| | - Massimo Mella
- Dipartimento di Scienza ed Alta Tecnologia, Università degli Studi dell'Insubria, via Valleggio 11, 22100 Como, Italy
| | - Marcel Drabbels
- Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Martí Pi
- Departament ECM, Facultat de Física, and INUB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
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18
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Modesto-Costa L, Canuto S, Mukherjee PK, Fricke B. A simple model for a theoretical study of the spectral line shifts of alkali atoms attached to helium nanodroplets. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2015.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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19
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von Vangerow J, John O, Stienkemeier F, Mudrich M. Dynamics of solvation and desolvation of rubidium attached to He nanodroplets. J Chem Phys 2015. [DOI: 10.1063/1.4926829] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J. von Vangerow
- Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany
| | - O. John
- 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
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20
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Mateo D, Leal A, Hernando A, Barranco M, Pi M, Cargnoni F, Mella M, Zhang X, Drabbels M. Communication: nucleation of quantized vortex rings in 4He nanodroplets. J Chem Phys 2015; 140:131101. [PMID: 24712773 DOI: 10.1063/1.4870245] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Whereas most of the phenomena associated with superfluidity have been observed in finite-size helium systems, the nucleation of quantized vortices has proven elusive. Here we show using time-dependent density functional simulations that the solvation of a Ba(+) ion created by photoionization of neutral Ba at the surface of a (4)He nanodroplet leads to the nucleation of a quantized ring vortex. The vortex is nucleated on a 10 ps timescale at the equator of a solid-like solvation structure that forms around the Ba(+) ion. The process is expected to be quite general and very efficient under standard experimental conditions.
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Affiliation(s)
- David Mateo
- Departament ECM, Facultat de Física, and INUB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Antonio Leal
- Departament ECM, Facultat de Física, and INUB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Alberto Hernando
- Laboratory of Theoretical Physical Chemistry, Institut des Sciences et Ingénierie Chimiques, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Manuel Barranco
- Departament ECM, Facultat de Física, and INUB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Martí Pi
- Departament ECM, Facultat de Física, and INUB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Fausto Cargnoni
- Istituto di Scienze e Tecnologie Molecolari (ISTM), Consiglio Nazionale delle Ricerche, via Golgi 19, 20133 Milano, Italy
| | - Massimo Mella
- Dipartimento di Scienza ed Alta Tecnologia, Università degli Studi dell'Insubria, via Valleggio 11, 22100 Como, Italy
| | - Xiaohang Zhang
- Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Marcel Drabbels
- Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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21
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Loginov E, Hernando A, Beswick JA, Halberstadt N, Drabbels M. Excitation of Sodium Atoms Attached to Helium Nanodroplets: The 3p ← 3s Transition Revisited. J Phys Chem A 2015; 119:6033-44. [DOI: 10.1021/jp511885t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - J. Alberto Beswick
- Laboratoire
des Collisions, Agrégats, Réactivité, IRSAMC, CNRS and Université Toulouse 3 Paul Sabatier, 31062 Toulouse, France
| | - Nadine Halberstadt
- Laboratoire
des Collisions, Agrégats, Réactivité, IRSAMC, CNRS and Université Toulouse 3 Paul Sabatier, 31062 Toulouse, France
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22
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Pentlehner D, Slenczka A. Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets. J Chem Phys 2015; 142:014311. [PMID: 25573565 DOI: 10.1063/1.4904899] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm(-1)) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time.
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Affiliation(s)
- D Pentlehner
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
| | - A Slenczka
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
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23
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24
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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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25
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Loginov E, Drabbels M. Dynamics of Excited Sodium Atoms Attached to Helium Nanodroplets. J Phys Chem A 2014; 118:2738-48. [DOI: 10.1021/jp4121996] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Evgeniy Loginov
- Laboratoire de Chimie Physique
Moléculaire, Ecole polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Marcel Drabbels
- Laboratoire de Chimie Physique
Moléculaire, Ecole polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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26
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Leal A, Mateo D, Hernando A, Pi M, Barranco M. Capture of heliophobic atoms by 4He nanodroplets: the case of cesium. Phys Chem Chem Phys 2014; 16:23206-13. [DOI: 10.1039/c4cp03297g] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Within Density Functional Theory (DFT), we address the capture of a Cs atom by a superfluid helium nanodroplet using models of different complexity.
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Affiliation(s)
- Antonio Leal
- Departament ECM
- Facultat de Física, and IN2UB
- Universitat de Barcelona
- 08028 Barcelona, Spain
| | - David Mateo
- Department of Chemistry and Biochemistry
- California State University at Northridge
- Northridge, USA
| | - Alberto Hernando
- Laboratory of Theoretical Physical Chemistry
- Institut des Sciences et Ingénierie Chimiques
- Swiss Federal Institute of Technology Lausanne (EPFL)
- CH-1015 Lausanne, Switzerland
| | - Martí Pi
- Departament ECM
- Facultat de Física, and IN2UB
- Universitat de Barcelona
- 08028 Barcelona, Spain
| | - Manuel Barranco
- Departament ECM
- Facultat de Física, and IN2UB
- Universitat de Barcelona
- 08028 Barcelona, Spain
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27
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Hernando A, Beswick JA, Halberstadt N. Communication: Angular momentum alignment and fluorescence polarization of alkali atoms photodetached from helium nanodroplets. J Chem Phys 2013; 139:221102. [DOI: 10.1063/1.4843235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Brauer NB, Smolarek S, Loginov E, Mateo D, Hernando A, Pi M, Barranco M, Buma WJ, Drabbels M. Critical Landau velocity in helium nanodroplets. PHYSICAL REVIEW LETTERS 2013; 111:153002. [PMID: 24160595 DOI: 10.1103/physrevlett.111.153002] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Indexed: 06/02/2023]
Abstract
The best-known property of superfluid helium is the vanishing viscosity that objects experience while moving through the liquid with speeds below the so-called critical Landau velocity. This critical velocity is generally considered a macroscopic property as it is related to the collective excitations of the helium atoms in the liquid. In the present work we determine to what extent this concept can still be applied to nanometer-scale, finite size helium systems. To this end, atoms and molecules embedded in helium nanodroplets of various sizes are accelerated out of the droplets by means of optical excitation, and the speed distributions of the ejected particles are determined. The measurements reveal the existence of a critical velocity in these systems, even for nanodroplets consisting of only a thousand helium atoms. Accompanying theoretical simulations based on a time-dependent density functional description of the helium confirm and further elucidate this experimental finding.
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Affiliation(s)
- Nils B Brauer
- Laboratoire de Chimie Physique Moléculaire, Ecole polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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29
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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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30
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Lackner F, Krois G, Ernst WE. Rydberg–Ritz analysis and quantum defects for Rb and Cs atoms on helium nanodroplets. Mol Phys 2013. [DOI: 10.1080/00268976.2013.788792] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Florian Lackner
- Institute of Experimental Physics, Graz University of Technology , Graz, Austria
| | - Günter Krois
- Institute of Experimental Physics, Graz University of Technology , Graz, Austria
| | - Wolfgang E. Ernst
- Institute of Experimental Physics, Graz University of Technology , Graz, Austria
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31
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Hauser AW, Gruber T, Filatov M, Ernst WE. Shifts in the ESR spectra of alkali-metal atoms (Li, Na, K, Rb) on helium nanodroplets. Chemphyschem 2013; 14:716-22. [PMID: 23125112 PMCID: PMC3648978 DOI: 10.1002/cphc.201200697] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 10/15/2012] [Indexed: 11/06/2022]
Abstract
He-droplet-induced changes of the hyperfine structure constants of alkali-metal atoms are investigated by a combination of relativistically corrected ab initio methods with a simulation of the helium density distribution based on He density functional theory. Starting from an accurate description of the variation of the hyperfine structure constant in the M-He diatomic systems (M=Li, Na, K, Rb) as a function of the interatomic distance we simulate the shifts induced by droplets of up to 10,000 (4)He atoms. All theoretical predictions for the relative shifts in the isotropic hyperfine coupling constants of the alkali-metal atoms attached to helium droplets of different size are then tied to a single, experimentally derived parameter of Rb.
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Affiliation(s)
- Andreas W Hauser
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
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32
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Pentlehner D, Slenczka A. Electronic spectroscopy of 9,10-dichloroanthracene inside helium droplets. J Chem Phys 2013; 138:024313. [PMID: 23320689 DOI: 10.1063/1.4773894] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The spectroscopy of molecules doped into superfluid helium droplets provides information on both, the dopant molecule and the helium environment. Electronic spectra of 9,10-dichloroanthracene in helium droplets are presented and compared with corresponding gas phase spectra to unravel the influence of the helium environment. The combined investigation of fluorescence excitation and dispersed emission provides information on dynamic processes in addition to energetic conditions. For vibronic states, the helium induced decay channels dominate over all intramolecular channels that contribute to the gas phase behavior. In addition to the triplet splitting caused by the Cl isotopes, a fine structure resolved for all transitions in the fluorescence excitation spectrum was found, which is the signature of microsolvation of this compound in helium droplets. This fine structure is identified as a single pure molecular transition accompanied by a sharply structured phonon wing. The corresponding fine structure measured for bare anthracene shows remarkable differences.
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Affiliation(s)
- D Pentlehner
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
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Mateo D, Hernando A, Barranco M, Loginov E, Drabbels M, Pi M. Translational dynamics of photoexcited atoms in 4He nanodroplets: the case of silver. Phys Chem Chem Phys 2013; 15:18388-400. [DOI: 10.1039/c3cp52221k] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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34
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Giese C, Mullins T, Grüner B, Weidemüller M, Stienkemeier F, Mudrich M. Formation and relaxation of RbHe exciplexes on He nanodroplets studied by femtosecond pump and picosecond probe spectroscopy. J Chem Phys 2012; 137:244307. [PMID: 23277936 DOI: 10.1063/1.4772749] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- C Giese
- Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany
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35
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Bünermann O, Kornilov O, Haxton DJ, Leone SR, Neumark DM, Gessner O. Ultrafast probing of ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets. J Chem Phys 2012; 137:214302. [DOI: 10.1063/1.4768422] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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36
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Hernando A, Masson A, Briant M, Mestdagh JM, Gaveau MA, Halberstadt N. Fluorescence emission of Ca-atom from photodissociated Ca2 in Ar doped helium droplets. II. Theoretical. J Chem Phys 2012; 137:184311. [PMID: 23163375 DOI: 10.1063/1.4762837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The stability of the ground or excited state calcium atom in an argon-doped helium droplet has been investigated using an extension of the helium density functional method to treat clusters. This work was motivated by the experimental study presented in a companion paper, hereafter called Paper I [A. Masson, M. Briant, J. M. Mestdagh, M. A. Gaveau, A. Hernando, and N. Halberstadt, J. Chem. Phys. 137, 184310 (2012)], which investigated Ca(2) photodissociation in an argon-doped helium droplet and the nature of the fluorescent species. It is found that one single argon atom is sufficient to bring the calcium atom inside the droplet, for droplets of over 200 helium atoms. The absorption and emission spectra of CaAr(M) (M = 0-7) clusters have been simulated using the recently developed density sampling method to describe the influence of the helium environment. Absorption spectra exhibit broad, double bands that are significantly blueshifted with respect to the calcium atomic line. The emission spectra are less broad and redshifted with respect to the calcium resonance line. The shifts are found to be additive only for M ≤ 2, because only the first two argon atoms are located in equivalent positions around the calcium p orbital. This finding gives a justification for the fit presented in the companion paper, which uses the observed shifts in the emission spectra as a function of argon pressure to deduce the shifts as a function of the number of argon atoms present in the cluster. An analysis of this fit is presented here, based on the calculated shifts. It is concluded that the emitting species following Ca(2) photodissociation in an argon-doped droplet in Paper I could be Ca∗Ar(M) in a partly evaporated droplet where less than 200 helium atoms remain.
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Affiliation(s)
- A Hernando
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09, France
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37
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Zhang X, Drabbels M. Communication: Barium ions and helium nanodroplets: Solvation and desolvation. J Chem Phys 2012; 137:051102. [DOI: 10.1063/1.4743900] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Aguirre NF, Mateo D, Mitrushchenkov AO, Pi M, de Lara-Castells MP. Helium mediated deposition: modeling the He-TiO2(110)-(1×1) interaction potential and application to the collision of a helium droplet from density functional calculations. J Chem Phys 2012; 136:124703. [PMID: 22462884 DOI: 10.1063/1.3698173] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This paper is the first of a two-part series dealing with quantum-mechanical (density-functional-based) studies of helium-mediated deposition of catalytic species on the rutile TiO(2)(110)-(1×1) surface. The interaction of helium with the TiO(2)(110)-(1×1) surface is first evaluated using the Perdew-Burke-Ernzerhof functional at a numerical grid dense enough to build an analytical three-dimensional potential energy surface. Three (two prototype) potential models for the He-surface interaction in helium scattering calculations are analyzed to build the analytical potential energy surface: (1) the hard-corrugated-wall potential model; (2) the corrugated-Morse potential model; and (3) the three-dimensional Morse potential model. Different model potentials are then used to study the dynamics upon collision of a (4)He(300) cluster with the TiO(2)(110) surface at zero temperature within the framework of a time-dependent density-functional approach for the quantum fluid [D. Mateo, D. Jin, M. Barranco, and M. Pi, J. Chem. Phys. 134, 044507 (2011)] and classical dynamics calculations. The laterally averaged density functional theory-based potential with an added long-range dispersion interaction term is further applied. At variance with classical dynamics calculations, showing helium droplet splashing out of the surface at impact, the time evolution of the macroscopic helium wave-function predicts that the helium droplet spreads on the rutile surface and leads to the formation of a thin film above the substrate. This work thus provides a basis for simulating helium mediated deposition of metallic clusters embedded within helium nanodroplets.
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Affiliation(s)
- Néstor F Aguirre
- Instituto de Física Fundamental (C.S.I.C.), Serrano 123, E-28006 Madrid, Spain
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Loginov E, Drabbels M. Spectroscopy and dynamics of barium-doped helium nanodroplets. J Chem Phys 2012; 136:154302. [PMID: 22519321 DOI: 10.1063/1.3701565] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Evgeniy Loginov
- Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne, CH-1015 Lausanne, Switzerland
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Poms J, Hauser AW, Ernst WE. Helium nanodroplets doped with xenon and rubidium atoms: a case study of van der Waals interactions between heliophilic and heliophobic dopants. Phys Chem Chem Phys 2012; 14:15158-65. [DOI: 10.1039/c2cp42333b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Fechner L, Grüner B, Sieg A, Callegari C, Ancilotto F, Stienkemeier F, Mudrich M. Photoionization and imaging spectroscopy of rubidium atoms attached to helium nanodroplets. Phys Chem Chem Phys 2012; 14:3843-51. [PMID: 22327348 DOI: 10.1039/c2cp22749e] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- L Fechner
- Physikalisches Institut, Universität Freiburg, Freiburg, Germany
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