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Milner AA, Apkarian VA, Milner V. Dynamics of molecular rotors in bulk superfluid helium. SCIENCE ADVANCES 2023; 9:eadi2455. [PMID: 37379388 PMCID: PMC10306291 DOI: 10.1126/sciadv.adi2455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/11/2023] [Indexed: 06/30/2023]
Abstract
Molecules immersed in liquid helium are excellent probes of superfluidity. Their electronic, vibrational, and rotational dynamics provide valuable clues about the superfluid at the nanoscale. Here we report on the experimental study of the laser-induced rotation of helium dimers inside the superfluid 4He bath at variable temperature. The coherent rotational dynamics of [Formula: see text] is initiated in a controlled way by ultrashort laser pulses and tracked by means of time-resolved laser-induced fluorescence. We detect the decay of rotational coherence on the nanosecond time scale and investigate the effects of temperature on the decoherence rate. The observed temperature dependence suggests a nonequilibrium evolution of the quantum bath, accompanied by the emission of the wave of second sound. The method offers ways of studying superfluidity with molecular nanoprobes under variable thermodynamic conditions.
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Affiliation(s)
- Alexander A. Milner
- Department of Physics and Astronomy, The University of British Columbia, Vancouver, Canada
| | - V. A. Apkarian
- Department of Chemistry, University of California, Irvine, California 92697, USA
| | - Valery Milner
- Department of Physics and Astronomy, The University of British Columbia, Vancouver, Canada
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Nijjar P, Krylov AI, Prezhdo OV, Vilesov AF, Wittig C. Triplet Excitons in Small Helium Clusters. J Phys Chem A 2019; 123:6113-6122. [DOI: 10.1021/acs.jpca.9b03241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Parmeet Nijjar
- Department of Chemistry, University of Southern California, 3620 McClintock Avenue, Los Angeles, California 90089-1062, United States
| | - Anna I. Krylov
- Department of Chemistry, University of Southern California, 3620 McClintock Avenue, Los Angeles, California 90089-1062, United States
| | - Oleg V. Prezhdo
- Department of Chemistry, University of Southern California, 3620 McClintock Avenue, Los Angeles, California 90089-1062, United States
| | - Andrey F. Vilesov
- Department of Chemistry, University of Southern California, 3620 McClintock Avenue, Los Angeles, California 90089-1062, United States
| | - Curt Wittig
- Department of Chemistry, University of Southern California, 3620 McClintock Avenue, Los Angeles, California 90089-1062, United States
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Nijjar P, Krylov AI, Prezhdo OV, Vilesov AF, Wittig C. Conversion of He(2 3 S) to He 2( a 3Σ u+) in Liquid Helium. J Phys Chem Lett 2018; 9:6017-6023. [PMID: 30272979 DOI: 10.1021/acs.jpclett.8b02454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The report of an anomalously intense He4+ peak in electron impact mass spectra of large helium droplets created a stir 3 decades ago that continues to this day. When the electron kinetic energy exceeds 41 eV, an additional pathway opens that yields He4+ predominantly in an electronically excited metastable state. A pair of He*(23 S) atoms has been implicated based on the isolated He* energy of 19.82 eV and the 41 eV threshold, and the creation of He4+ has been conjectured to proceed via a pair of He2*( a3Σ u+) precursors. The mechanism whereby He* converts to He2* in liquid helium has remained a mystery, however. High level ab initio theory combined with classical molecular dynamics has been applied to systems comprising small numbers of He atoms. The conversion of He* to He2* in such systems is shown to be due to a simple many-body effect that yields He2* rapidly and efficiently.
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Affiliation(s)
- P Nijjar
- Department of Chemistry , University of Southern California , 3620 McClintock Avenue , Los Angeles , California 90089-1062 , United States
| | - A I Krylov
- Department of Chemistry , University of Southern California , 3620 McClintock Avenue , Los Angeles , California 90089-1062 , United States
| | - O V Prezhdo
- Department of Chemistry , University of Southern California , 3620 McClintock Avenue , Los Angeles , California 90089-1062 , United States
| | - A F Vilesov
- Department of Chemistry , University of Southern California , 3620 McClintock Avenue , Los Angeles , California 90089-1062 , United States
| | - C Wittig
- Department of Chemistry , University of Southern California , 3620 McClintock Avenue , Los Angeles , California 90089-1062 , United States
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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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Aitken F, Volino F, Mendoza-Luna LG, Haeften KV, Eloranta J. A thermodynamic model to predict electron mobility in superfluid helium. Phys Chem Chem Phys 2017; 19:15821-15832. [PMID: 28585629 DOI: 10.1039/c7cp03067c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron mobility in superfluid helium is modeled between 0.1 and 2.2 K by a van der Waals-type thermodynamic equation of state, which relates the free volume of solvated electrons to temperature, density, and phase dependent internal pressure. The model is first calibrated against known electron mobility reference data along the saturated vapor pressure line and then validated to reproduce the existing mobility literature values as a function of pressure and temperature with at least 10% accuracy. Four different electron mobility regimes are identified: (1) Landau critical velocity limit (T ≈ 0), (2) mobility limited by thermal phonons (T < 0.6 K), (3) thermal phonon and discrete roton scattering ("roton gas") limited mobility (0.6 K < T < 1.2 K), and (4) the viscous liquid ("roton continuum") limit (T > 1.2 K) where the ion solvation structure directly determines the mobility. In the latter regime, the Stokes equation can be used to estimate the hydrodynamic radius of the solvated electron based on its mobility and fluid viscosity. To account for the non-continuum behavior appearing below 1.2 K, the temperature and density dependent Millikan-Cunningham factor is introduced. The hydrodynamic electron bubble radii predicted by the present model appear generally larger than the solvation cavity interface barycenter values obtained from density functional theory (DFT) calculations. Based on the classical Stokes law, this difference can arise from the variation of viscosity and flow characteristics around the electron. The calculated DFT liquid density profiles show distinct oscillations at the vacuum/liquid interface, which increase the interface rigidity.
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Affiliation(s)
- Frédéric Aitken
- Univ. Grenoble Alpes, CNRS, Grenoble INP, G2ELab, F-38000 Grenoble, France.
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Bonifaci N, Li Z, Eloranta J, Fiedler SL. Interaction of Helium Rydberg State Molecules with Dense Helium. J Phys Chem A 2016; 120:9019-9027. [PMID: 27783517 DOI: 10.1021/acs.jpca.6b08412] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The interaction potentials of the He2* excimer, in the a3Σu, b3Πg, c3Σg, and d3Σu electronic states with a ground state helium atom are presented. The symmetry of the interaction potentials closely follows the excimer Rydberg electron density with pronounced short-range minima appearing along the nodal planes of the Rydberg orbital. In such cases, a combination of the electrostatic short-range attraction combined with Pauli repulsion leads to the appearance of unusual long-range maxima in the potentials. Bosonic density functional calculations show that the 3d state excimer resides in a localized solvation bubble in dense helium at 4.5 K, with radii varying from 12.7 Å at 0.1 MPa to 10.8 Å at 2.4 MPa. The calculated 3d → 3b pressure-induced fluorescence band shifts are in good agreement with experimental results determined by application of corona discharge. The magnitude of the spectral shifts indicate that the observed He2* molecules emit from dense helium whereas the corresponding fluorescence signal from the discharge zone appears quenched. This implies that fluorescence spectroscopy involving this electronic transition can only be used to probe the state of the surrounding medium rather than the discharge zone itself.
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Affiliation(s)
- Nelly Bonifaci
- G2ELab-GreEn-ER, Equipe MDE , 21 avenue des Martyrs, CS 90624, 38031 Grenoble Cedex 1, France
| | - Zhiling Li
- Guizhou Institute of Technology 1 Caiguan Road, 550003 Guiyang, China
| | - Jussi Eloranta
- Department of Chemistry and Biochemistry, California State University at Northridge , 18111 Nordhoff St., Northridge, California 91330, United States
| | - Steven L Fiedler
- Department of Biology and Chemistry, Fitchburg State University , 160 Pearl St., Fitchburg, Massachusetts 01420, United States
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Mateo D, Eloranta J, Williams GA. Interaction of ions, atoms, and small molecules with quantized vortex lines in superfluid 4He. J Chem Phys 2015; 142:064510. [DOI: 10.1063/1.4907597] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- David Mateo
- Department of Chemistry and Biochemistry, California State University at Northridge, 18111 Nordhoff St., Northridge, California 91330, USA
| | - Jussi Eloranta
- Department of Chemistry and Biochemistry, California State University at Northridge, 18111 Nordhoff St., Northridge, California 91330, USA
| | - Gary A. Williams
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
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Popov E, Mammetkuliyev M, Eloranta J. Dynamics of vortex assisted metal condensation in superfluid helium. J Chem Phys 2013; 138:204307. [DOI: 10.1063/1.4807382] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Zmeev DE, Pakpour F, Walmsley PM, Golov AI, Guo W, McKinsey DN, Ihas GG, McClintock PVE, Fisher SN, Vinen WF. Excimers He2* as tracers of quantum turbulence in 4He in the t = 0 limit. PHYSICAL REVIEW LETTERS 2013; 110:175303. [PMID: 23679742 DOI: 10.1103/physrevlett.110.175303] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Indexed: 06/02/2023]
Abstract
We have studied the interaction of metastable 4He2* excimer molecules with quantized vortices in superfluid 4He in the zero temperature limit. The vortices were generated by either rotation or ion injection. The trapping diameter of the molecules on quantized vortices was found to be 96±6 nm at a pressure of 0.1 bar and 27±5 nm at 5.0 bar. We have also demonstrated that a moving tangle of vortices can carry the molecules through the superfluid helium.
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Affiliation(s)
- D E Zmeev
- School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, United Kingdom
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Wang CC, Kornilov O, Gessner O, Kim JH, Peterka DS, Neumark DM. Photoelectron Imaging of Helium Droplets Doped with Xe and Kr Atoms. J Phys Chem A 2008; 112:9356-65. [DOI: 10.1021/jp802332f] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chia C. Wang
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Oleg Kornilov
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Oliver Gessner
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Jeong Hyun Kim
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Darcy S. Peterka
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Daniel M. Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
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Tiggesbäumker J, Stienkemeier F. Formation and properties of metal clusters isolated in helium droplets. Phys Chem Chem Phys 2007; 9:4748-70. [PMID: 17712454 DOI: 10.1039/b703575f] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The unique conditions forming atomic and molecular complexes and clusters using superfluid helium nanodroplets have opened up an innovative route for studying the physical and chemical properties of matter on the nanoscale. This review summarizes the specific characteristics of the formation of atomic clusters partly generated far from equilibrium in the helium environment. Special emphasis is on the optical response, electronic properties as well as dynamical processes which are mostly affected by the surrounding quantum matrix. Experiments include the optical induced response of isolated cluster systems in helium under quite different excitation conditions ranging from the linear regime up to the violent interaction with a strong laser field leading to Coulomb explosion and the generation of highly charged atomic fragments. The variety of results on the outstanding properties in the quantum size regime highlights the peculiar capabilities of helium nanodroplet isolation spectroscopy.
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Sethumadhavan B, Yao W, Huang YH, Lanou RE, Maris HJ, Seidel GM. Electrical breakdown in helium cells at low temperature. PHYSICAL REVIEW LETTERS 2006; 97:015301. [PMID: 16907382 DOI: 10.1103/physrevlett.97.015301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Indexed: 05/11/2023]
Abstract
Electrical breakdown of partially filled helium cells below 0.5 K is shown to be the result of Penning ionization of metastable triplet helium excimers bound to the surface of the liquid.
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Affiliation(s)
- B Sethumadhavan
- Physics Department, Brown University, Providence, Rhode Island 02912, USA
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Polyakova E, Stolyarov D, Wittig C. Multiple photon excitation and ionization of NO in and on helium droplets. J Chem Phys 2006; 124:214308. [PMID: 16774408 DOI: 10.1063/1.2198844] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The photoexcitation of NO embedded in superfluid Hen nanodroplets having n approximately 10(4) has been examined. Two-photon excitation prepares electronically excited states (NO(*)), most notably, the embedded analog of the A 2Sigma state of gas phase NO. Vertical excitation to this low Rydberg state is blueshifted and broadened relative to its gas phase counterpart because of the repulsive electron-helium interaction. Transport to the droplet surface is believed to be facile in the superfluid. For example, NO* prefers (energetically) to reside at the droplet surface rather than at the droplet center, in contrast to NO. Photoionization of surface-bound NO* occurs over a significant photon energy range. This yields small cluster ions NO+Hek) with approximately 90% of these clusters having k< or =10. The variation of ion yield with photon energy displays a precipitous change in the region of 24 300-24 400 cm(-1) for all values of k. Possible photoionization mechanisms are discussed and it is suggested that intermediate levels with high-n Rydberg character play a role. This work underscores the important role played by transport in the photophysics of species embedded in the superfluid host.
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Affiliation(s)
- E Polyakova
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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Chang DT, Gellene GI. An ab initio, analytically fitted, global potential energy surface for the ground electronic state of He3+. J Chem Phys 2003. [DOI: 10.1063/1.1594711] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Eloranta J, Apkarian VA. A time dependent density functional treatment of superfluid dynamics: Equilibration of the electron bubble in superfluid 4He. J Chem Phys 2002. [DOI: 10.1063/1.1520139] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Benderskii AV, Eloranta J, Zadoyan R, Apkarian VA. A direct interrogation of superfluidity on molecular scales. J Chem Phys 2002. [DOI: 10.1063/1.1485955] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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