1
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Ben Ltaief L, Sishodia K, Mandal S, De S, Krishnan SR, Medina C, Pal N, Richter R, Fennel T, Mudrich M. Efficient Indirect Interatomic Coulombic Decay Induced by Photoelectron Impact Excitation in Large Pure Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2023; 131:023001. [PMID: 37505945 DOI: 10.1103/physrevlett.131.023001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 06/05/2023] [Indexed: 07/30/2023]
Abstract
Ionization of matter by energetic radiation generally causes complex secondary reactions that are hard to decipher. Using large helium nanodroplets irradiated by extreme ultraviolet (XUV) photons, we show that the full chain of processes ensuing primary photoionization can be tracked in detail by means of high-resolution electron spectroscopy. We find that elastic and inelastic scattering of photoelectrons efficiently induces interatomic Coulombic decay (ICD) in the droplets. This type of indirect ICD even becomes the dominant process of electron emission in nearly the entire XUV range in large droplets with radius ≳40 nm. Indirect ICD processes induced by electron scattering likely play an important role in other condensed-phase systems exposed to ionizing radiation as well, including biological matter.
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Affiliation(s)
- L Ben Ltaief
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - K Sishodia
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - S Mandal
- Indian Institute of Science Education and Research, Pune 411008, India
| | - S De
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - S R Krishnan
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - C Medina
- Institute of Physics, University of Freiburg, 79104 Freiburg, Germany
| | - N Pal
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - R Richter
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - T Fennel
- Institute for Physics, University of Rostock, 18051 Rostock, Germany
| | - M Mudrich
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
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2
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von Haeften K, Laarmann T, Wabnitz H, Möller T. Relaxation dynamics of 3He and 4He clusters and droplets studied using near infrared and visible fluorescence excitation spectroscopy. Phys Chem Chem Phys 2023; 25:1863-1880. [PMID: 36541224 DOI: 10.1039/d2cp04594j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The relaxation dynamics of electronically excited 3He and 4He clusters and droplets is investigated using time-correlated near-infrared and visible (NIR/VIS) fluorescence excitation spectroscopy. A rich data set spanning a wide range of cluster and droplet sizes is produced. The spectral features broadly follow the vacuum ultraviolet excitation (VUV) spectra. However, when the NIR/VIS spectra are normalised to the VUV fluorescence, regions with distinctly different cluster size and isotope dependence are identified, enabling deeper insight into the relaxation mechanism. Particle density, location of atomic-like states and their principal quantum number, n, are found to play an important role in the relaxation. For states with n = 3 and higher, only energy within the surface region is transferred to excited atoms which are subsequently ejected from the surface and fluoresce in vacuum. For states with n = 2, energy from the entire region within clusters and droplets is transferred to the surface, leading to the ejection of excited atoms and excimers. Here, the energy is transferred by excitation hopping, which competes with radiative and non-radiative decay, making ejection and NIR/VIS fluorescence inefficient in increasingly larger droplets.
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3
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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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4
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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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5
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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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6
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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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7
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Thaler B, Ranftl S, Heim P, Cesnik S, Treiber L, Meyer R, Hauser AW, Ernst WE, Koch M. Femtosecond photoexcitation dynamics inside a quantum solvent. Nat Commun 2018; 9:4006. [PMID: 30275442 PMCID: PMC6167364 DOI: 10.1038/s41467-018-06413-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 08/29/2018] [Indexed: 11/13/2022] Open
Abstract
The observation of chemical reactions on the time scale of the motion of electrons and nuclei has been made possible by lasers with ever shortened pulse lengths. Superfluid helium represents a special solvent that permits the synthesis of novel classes of molecules that have eluded dynamical studies so far. However, photoexcitation inside this quantum solvent triggers a pronounced response of the solvation shell, which is not well understood. Here, we present a mechanistic description of the solvent response to photoexcitation of indium (In) dopant atoms inside helium nanodroplets (HeN), obtained from femtosecond pump–probe spectroscopy and time-dependent density functional theory simulations. For the In–HeN system, part of the excited state electronic energy leads to expansion of the solvation shell within 600 fs, initiating a collective shell oscillation with a period of about 30 ps. These coupled electronic and nuclear dynamics will be superimposed on intrinsic photoinduced processes of molecular systems inside helium droplets. Femtosecond laser spectroscopy has contributed to our understanding of structure and function of matter. Here, the authors explore the applicability of superfluid helium nanodroplets as a sample preparation method that allows investigation of previously inaccessible classes of tailor-made or fragile molecular systems.
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Affiliation(s)
- Bernhard Thaler
- 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
| | - Pascal Heim
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010, Graz, Austria
| | - Stefan Cesnik
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010, Graz, Austria
| | - Leonhard Treiber
- 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
| | - Andreas W Hauser
- 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
| | - Markus Koch
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010, Graz, Austria.
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8
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Mendoza-Luna LG, Shiltagh NMK, Watkins MJ, Bonifaci N, Aitken F, von Haeften K. Excimers in the Lowest Rotational Quantum State in Liquid Helium. J Phys Chem Lett 2016; 7:4666-4670. [PMID: 27809539 DOI: 10.1021/acs.jpclett.6b02081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Evidence for helium excimers (He2*) in the lowest allowed rotational quantum state in liquid helium is presented. He2* was generated by a corona discharge in the gas and normal liquid phases. Fluorescence spectra recorded in the visible region between 3.8 and 5.0 K and 0.2 and 5.6 bar showed the rotationally resolved d3Σu+ → b3Πg transition of He2*. Analysis of the pressure and temperature dependence of lineshifts and line intensities showed features of solvated He2* superimposed on its gas-phase spectrum and, in the liquid phase only, pressure-induced rotational cooling. These findings suggest that He2* can be used to investigate bulk helium in different phases at the nanoscale.
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Affiliation(s)
- Luis Guillermo Mendoza-Luna
- Department of Physics and Astronomy, University of Leicester , University Road, Leicester LE1 7RH, United Kingdom
| | - Nagham M K Shiltagh
- Department of Physics and Astronomy, University of Leicester , University Road, Leicester LE1 7RH, United Kingdom
- Department of Physics, College of Science, University of Kerbala , Karbala, Iraq
| | - Mark J Watkins
- Department of Physics and Astronomy, University of Leicester , University Road, Leicester LE1 7RH, United Kingdom
| | - Nelly Bonifaci
- G2ELab-CNRS Equipe MDE, 25 Av. des Martyrs BP 166, 38042 Grenoble Cedex 9, France
| | - Frédéric Aitken
- G2ELab-CNRS Equipe MDE, 25 Av. des Martyrs BP 166, 38042 Grenoble Cedex 9, France
| | - Klaus von Haeften
- Department of Physics and Astronomy, University of Leicester , University Road, Leicester LE1 7RH, United Kingdom
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9
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Ziemkiewicz MP, Neumark DM, Gessner O. Ultrafast electronic dynamics in helium nanodroplets. INT REV PHYS CHEM 2015. [DOI: 10.1080/0144235x.2015.1051353] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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10
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Buchta D, Krishnan SR, Brauer NB, Drabbels M, O’Keeffe P, Devetta M, Di Fraia M, Callegari C, Richter R, Coreno M, Prince KC, Stienkemeier F, Ullrich J, Moshammer R, Mudrich M. Extreme ultraviolet ionization of pure He nanodroplets: Mass-correlated photoelectron imaging, Penning ionization, and electron energy-loss spectra. J Chem Phys 2013; 139:084301. [DOI: 10.1063/1.4818531] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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11
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Mateo D, Pi M, Navarro J, Toennies JP. A density functional study of the structure of small OCS@3HeN clusters. J Chem Phys 2013; 138:044321. [DOI: 10.1063/1.4788828] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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12
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Sartakov BG, Toennies JP, Vilesov AF. Infrared spectroscopy of carbonyl sulfide inside a pure3He droplet. J Chem Phys 2012; 136:134316. [DOI: 10.1063/1.3697475] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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13
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An der Lan L, Bartl P, Leidlmair C, Jochum R, Denifl S, Echt O, Scheier P. Solvation of Na+, K+, and their dimers in helium. Chemistry 2012; 18:4411-8. [PMID: 22374575 PMCID: PMC3350777 DOI: 10.1002/chem.201103432] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Indexed: 11/10/2022]
Abstract
Helium atoms bind strongly to alkali cations which, when embedded in liquid helium, form so-called snowballs. Calculations suggest that helium atoms in the first solvation layer of these snowballs form rigid structures and that their number (n) is well defined, especially for the lighter alkalis. However, experiments have so far failed to accurately determine values of n. We present high-resolution mass spectra of Na+Hen, K+Hen, Na2+Hen and K2+Hen, formed by electron ionization of doped helium droplets; the data allow for a critical comparison with several theoretical studies. For sodium and potassium monomers the spectra indicate that the value of n is slightly smaller than calculated. Na2+Hen displays two distinct anomalies at n=2 and n=6, in agreement with theory; dissociation energies derived from experiment closely track theoretical values. K2+Hen distributions are fairly featureless, which also agrees with predictions.
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Affiliation(s)
- Lukas An der Lan
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
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14
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von Haeften K, Laarmann T, Wabnitz H, Möller T, Fink K. Size and Isotope Effects of Helium Clusters and Droplets: Identification of Surface and Bulk-Volume Excitations. J Phys Chem A 2011; 115:7316-26. [DOI: 10.1021/jp2008489] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Klaus von Haeften
- Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Tim Laarmann
- Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg, Germany
| | | | - Thomas Möller
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Karin Fink
- Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe, Germany
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15
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Aitken F, Li ZL, Bonifaci N, Denat A, von Haeften K. Electron mobility in liquid and supercritical helium measured using corona discharges: a new semi-empirical model for cavity formation. Phys Chem Chem Phys 2011; 13:719-24. [PMID: 21052578 DOI: 10.1039/c0cp00786b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron mobilities in supercritical and liquid helium were investigated as a function of the density. The mobilities were derived from I(V) curves measured in a high-pressure cryogenic cell using a corona discharge in point-plane electrode geometry for charge generation. The presented data spans a wide pressure and temperature range due to the versatility of our experimental set-up. Where data from previous investigations is available for comparison, very good agreement is found. We present a semi-empirical model to calculate electron mobilities both in the liquid and supercritical phase. This model requires the electron-helium scattering length and thermodynamic state equations as the only input and circumvents any need to consider surface tension. Our semi-empirical model reproduces experimental data very well, in particular towards lower densities where transitions from localised to delocalised electron states were observed.
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Affiliation(s)
- F Aitken
- G2ELab-CNRS, 25 rue des Martyrs, 38042 Grenoble, France.
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16
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Closser KD, Head-Gordon M. Ab initio calculations on the electronically excited states of small helium clusters. J Phys Chem A 2010; 114:8023-32. [PMID: 20684573 DOI: 10.1021/jp103532q] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The vertical excitation energies of small helium clusters, He(7) and He(25), have been calculated using configuration interaction singles, and the character of the excited states was determined using attachment/detachment density analysis. It was found that in the n = 2 manifold the excitations could be interpreted as superpositions of atomic states, with excitations on the surface of the clusters being lower in energy than those in the bulk. For the n = 2 excited states with significant density on the interior of the cluster, mixing with the atomic n = 3 states resulted in lower excitation energies. For the n = 3 states the spatial extent of the excited-state density can be much larger than the size of the cluster, making analysis of the states more difficult and highly dependent on the internuclear distance. Introducing disorder into the clusters results in some localization of the excited states, although highly delocalized states are always observed in these small clusters. In addition, experimental results for small clusters are interpreted in terms of these findings.
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Affiliation(s)
- Kristina D Closser
- Department of Chemistry, University of California at Berkeley, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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17
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Kornilov O, Wang CC, Bünermann O, Healy AT, Leonard M, Peng C, Leone SR, Neumark DM, Gessner O. Ultrafast Dynamics in Helium Nanodroplets Probed by Femtosecond Time-Resolved EUV Photoelectron Imaging. J Phys Chem A 2009; 114:1437-45. [DOI: 10.1021/jp907312t] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Oleg Kornilov
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Chia C. Wang
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Oliver Bünermann
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Andrew T. Healy
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Mathew Leonard
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Chunte Peng
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Stephen R. Leone
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Daniel M. Neumark
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Oliver Gessner
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, University of California, Berkeley, California 94720
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18
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Peterka DS, Kim JH, Wang CC, Neumark DM. Photoionization and Photofragmentation of SF6 in Helium Nanodroplets. J Phys Chem B 2006; 110:19945-55. [PMID: 17020381 DOI: 10.1021/jp062195o] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photoionization of He droplets doped with SF6 was investigated using tunable vacuum ultraviolet (VUV) synchrotron radiation from the Advanced Light Source (ALS). The resulting ionization and photofragmentation dynamics were characterized using time-of-flight mass spectrometry combined with photofragment and photoelectron imaging. Results are compared to those of gas-phase SF6 molecules. We find dissociative photoionization to SF5+ to be the dominant channel, in agreement with previous results. Key new findings are that (a) the photoelectron spectrum of the SF6 in the droplet is similar but not identical to that of the gas-phase species, (b) the SF5+ photofragment velocity distribution is considerably slower upon droplet photoionization, and (c) fragmentation to SF4+ and SF3+ is much less than in the photoionization of bare SF6. From these measurements we obtain new insights into the mechanism of SF6 photoionization within the droplet and the cooling of the hot photofragment ions produced by dissociative photoionization.
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Affiliation(s)
- Darcy S Peterka
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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19
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Kim JH, Peterka DS, Wang CC, Neumark DM. Photoionization of helium nanodroplets doped with rare gas atoms. J Chem Phys 2006; 124:214301. [PMID: 16774401 DOI: 10.1063/1.2202313] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Photoionization of He droplets doped with rare gas atoms (Rg=Ne, Ar, Kr, and Xe) was studied by time-of-flight mass spectrometry, utilizing synchrotron radiation from the Advanced Light Source from 10 to 30 eV. High resolution mass spectra were obtained at selected photon energies, and photoion yield curves were measured for several ion masses (or ranges of ion masses) over a wide range of photon energies. Only indirect ionization of the dopant rare gas atoms was observed, either by excitation or charge transfer from the surrounding He atoms. Significant dopant ionization from excitation transfer was seen at 21.6 eV, the maximum of He 2p 1P absorption band for He droplets, and from charge transfer above 23 eV, the threshold for ionization of pure He droplets. No Ne+ or Ar+ signal from droplet photoionization was observed, but peaks from HenNe+ and HenAr+ were seen that clearly originated from droplets. For droplets doped with Rg=Kr or Xe, both Rg+ and HenRg+ ions were observed. For all rare gases, Rg2+ and HenRgm+ (n,m> or =1) were produced by droplet photoionization. Mechanisms of dopant ionization and subsequent dynamics are discussed.
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Affiliation(s)
- Jeong Hyun Kim
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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20
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Peterka DS, Lindinger A, Poisson L, Ahmed M, Neumark DM. Photoelectron imaging of helium droplets. PHYSICAL REVIEW LETTERS 2003; 91:043401. [PMID: 12906657 DOI: 10.1103/physrevlett.91.043401] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2002] [Indexed: 05/24/2023]
Abstract
The photoionization and photoelectron spectroscopy of He nanodroplets (10(4) atoms) has been studied by photoelectron imaging with photon energies from 22.5-24.5 eV. Total electron yield measurements reveal broad features, whose onset is approximately 1.5 eV below the ionization potential of atomic He. The photoelectron spectra are dominated by very low energy electrons, with <E(k)> less than 0.6 meV. These results are attributed to the formation and autoionization of highly vibrationally excited He(*)(n) Rydberg states within the cluster, followed by strong final state interactions between the photoelectron and the droplet.
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Affiliation(s)
- Darcy S Peterka
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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