1
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Raston PL, Douberly GE. Infrared Laser Stark Spectroscopy of Methyl Fluoride in 4He Nanodroplets. Chemphyschem 2024; 25:e202400224. [PMID: 38511250 DOI: 10.1002/cphc.202400224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/20/2024] [Accepted: 03/20/2024] [Indexed: 03/22/2024]
Abstract
We measured the rotationally resolved infrared spectra of helium solvated methyl fluoride at 3 μm and 10 μm, wherein lies C-H and C-F stretching bands, respectively. The linewidths (FWHM) were found to increase with increasing vibrational energy and range from 0.002 cm-1 in the v3 band (C-F stretch) at ~1047 cm-1, to 0.65 cm-1 in the v4 band (asymmetric C-H stretch) at ~2997 cm-1. In between these two bands we observed the lower and upper components of the Fermi triad bands (ν1/2ν2/2ν5) at ~2859 and ~2961 cm-1. We carried out Stark spectroscopy on the lower band on account of its narrower linewidths (0.04 vs. 0.14 cm-1, respectively). The objective of performing Stark spectroscopy was to see if there is any evidence for a rotational linewidth dependence on the external field strength, due to a reduced difference in between methyl fluorides rotational energy gap and the roton-gap of superfluid helium. We did not find any evidence for such an effect, which we largely attribute to the rotational energy gap not increasing significantly enough by the external field. We point to another molecule (formaldehyde) whose energy levels are predicted to show a more promising response to application of an external field.
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Affiliation(s)
- Paul L Raston
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, United States
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA, 22807, United States
| | - Gary E Douberly
- Department of Chemistry, University of Georgia, Athens, GA, 30602, United States
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2
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Liu YY, Cui Y, Zhang XZ, Yang RB, Li ZQ, Wang ZW. Theory of all-coupling angulon for molecules rotating in many-body environment. J Chem Phys 2023; 159:114305. [PMID: 37721329 DOI: 10.1063/5.0162004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/25/2023] [Indexed: 09/19/2023] Open
Abstract
The formation of angulon, stemming from the rotor (molecule or impurity), rotating in the quantum many-body field, adds a new member to the quasi-particles' family and has aroused intense interest in multiple research fields. However, the analysis of the coupling strength between the rotor and its hosting environment remains a challenging task, both in theory and experiment. Here, we develop the all-coupling theory of the angulon by introducing a unitary transformation, where the renormalization of the rotational constants for different molecules in the helium nanodroplets is reproduced, getting excellent agreement with the experimental data collected during the past decades. Moreover, the strength of molecule-helium coupling and the effective radius of the solvation shell co-rotating along with the molecular rotor could be estimated qualitatively. This model not only provides significant enlightenment for analyzing the rotational spectroscopy of molecules in the phononic environment, but also provides a new method to study the transfer of the phonon angular momentum in the angulon frame.
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Affiliation(s)
- Yi-Yan Liu
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China
| | - Yu Cui
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China
| | - Xiao-Zhe Zhang
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China
| | - Ran-Bo Yang
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China
| | - Zhi-Qing Li
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China
| | - Zi-Wu Wang
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, School of Science, Tianjin University, Tianjin 300354, China
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3
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King KE, Franke PR, Pullen GT, Schaefer HF, Douberly GE. Helium Droplet Infrared Spectroscopy of the Butyl Radicals. J Chem Phys 2022; 157:084311. [DOI: 10.1063/5.0102287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Butyl radicals ( n-, s-, i-,} and tert-butyl) are formed from the pyrolysis of stable precursors (1-pentyl nitrite, 2-methyl-1-butyl nitrite, isopentyl nitrite, and azo- tert-butane, respectively). The radicals are doped into a beam of liquid helium droplets and probed with infrared action spectroscopy from 2700-3125 cm-1, allowing for a low temperature measurement of the CH stretching region. The presence of anharmonic resonance polyads in the 2800-3000 cm-1 region complicates its interpretation. To facilitate spectral assignment, the anharmonic resonances are modeled with two model Hamiltonian approaches that explicitly couple CH stretch fundamentals to HCH bend overtones and combinations: a VPT2+K normal mode model based on CCSD(T) quartic force fields and a semi-empirical local mode model. Both of these computational methods provide generally good agreement with the experimental spectra.
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Affiliation(s)
- Kale E King
- University of Georgia, United States of America
| | | | | | - Henry F. Schaefer
- Center for Computational Quantum Chemistry, University of Georgia, United States of America
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, United States of America
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4
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Blancafort-Jorquera M, Vilà A, González M. Rotational energy relaxation quantum dynamics of a diatomic molecule in a superfluid helium nanodroplet and study of the hydrogen isotopes case. Phys Chem Chem Phys 2019; 21:21007-21021. [PMID: 31528895 DOI: 10.1039/c9cp00952c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The rotational energy relaxation (RER) of a molecule X2(j,mj) in a 4He superfluid nanodroplet [HeND or (4He)N; T = 0.37 K] has been investigated using a hybrid quantum dynamics approach recently proposed by us. As far as we know, this is the first theoretical study about rotational relaxation inside HeNDs, and here several (real and hypothetical) isotopes of H2 have been examined, in order to analyze the influence of the rotational constant Be of these fast rotors on the dynamics. The structure of the nanodroplet practically does not change during the RER process, which approximately takes place according to a cascade mechanism j → j - 2; j - 2 → j - 4; …; 2 → 0, and mj is conserved. The results are consistent with the very scarce estimated experimental data available. The lifetime of an excited rotational state (≈1.0-7.6 ns) increases when: (a) Be increases; (b) j increases; and (c) N decreases (above N = 100 there is a small influence of N on the lifetime). This also applies to the global relaxation time and transition time. The analysis of the influence of the coupling between the j and j - 2 rotational states (due to the X2-helium interaction) and the X2 angular velocity on the lifetime and related properties has been helpful to better understand the dynamics. In contrast to the RER results, for the vibrational energy relaxation (VER) in HeNDs, when the quantum number v increases a decrease is observed in the lifetime of the excited vibrational state. This difference can be interpreted taking into account that RER and VER are associated with very different types of motion. Besides, in VER the intermediate excited states show metastability, differing from the RER case. We hope that the present study will encourage more studies to be developed on the RER dynamics in HeNDs, a basic, interesting and difficult to study physical phenomenon about which we still know very little.
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Affiliation(s)
- Miquel Blancafort-Jorquera
- Departament de Ciència de Materials i Química Física and IQTC, Universitat de Barcelona, Martí i Franquès, 1-11, 08028 Barcelona, Spain.
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5
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Brown AR, Brice JT, Franke PR, Douberly GE. Infrared Spectrum of Fulvenallene and Fulvenallenyl in Helium Droplets. J Phys Chem A 2019; 123:3782-3792. [DOI: 10.1021/acs.jpca.9b01661] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alaina R. Brown
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Joseph T. Brice
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Peter R. Franke
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
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6
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Miller I, Faulkner T, Raston PL. Laser Spectroscopy of Methanol Isotopologues in 4He Nanodroplets: Probing the Inertial Response around a Moderately Light Rotor. J Phys Chem A 2019; 123:1630-1636. [DOI: 10.1021/acs.jpca.8b12576] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Isaac Miller
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
| | - Ty Faulkner
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
| | - Paul L. Raston
- Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
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7
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Rzadkowski W, Lemeshko M. Effect of a magnetic field on molecule–solvent angular momentum transfer. J Chem Phys 2018; 148:104307. [DOI: 10.1063/1.5017591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Wojciech Rzadkowski
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warszawa, Poland
| | - Mikhail Lemeshko
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
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8
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Faulkner T, Miller I, Raston PL. Quantum cascade laser spectroscopy of OCS isotopologues in 4He nanodroplets: A test of adiabatic following for a heavy rotor. J Chem Phys 2018; 148:044308. [DOI: 10.1063/1.5009908] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ty Faulkner
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, USA
| | - Isaac Miller
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, USA
| | - Paul L. Raston
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, USA
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9
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Lemeshko M. Quasiparticle Approach to Molecules Interacting with Quantum Solvents. PHYSICAL REVIEW LETTERS 2017; 118:095301. [PMID: 28306270 DOI: 10.1103/physrevlett.118.095301] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Indexed: 06/06/2023]
Abstract
Understanding the behavior of molecules interacting with superfluid helium represents a formidable challenge and, in general, requires approaches relying on large-scale numerical simulations. Here, we demonstrate that experimental data collected over the last 20 years provide evidence that molecules immersed in superfluid helium form recently predicted angulon quasiparticles [Phys. Rev. Lett. 114, 203001 (2015)PRLTAO0031-900710.1103/PhysRevLett.114.203001]. Most important, casting the many-body problem in terms of angulons amounts to a drastic simplification and yields effective molecular moments of inertia as straightforward analytic solutions of a simple microscopic Hamiltonian. The outcome of the angulon theory is in good agreement with experiment for a broad range of molecular impurities, from heavy to medium-mass to light species. These results pave the way to understanding molecular rotation in liquid and crystalline phases in terms of the angulon quasiparticle.
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Affiliation(s)
- Mikhail Lemeshko
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria and Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
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10
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Redchenko ES, Lemeshko M. Libration of Strongly‐Oriented Polar Molecules inside a Superfluid. Chemphyschem 2016; 17:3649-3654. [DOI: 10.1002/cphc.201601042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Indexed: 11/06/2022]
Affiliation(s)
- E. S. Redchenko
- IST Austria (Institute of Science and Technology Austria) Am Campus 1 3400 Klosterneuburg Austria
| | - Mikhail Lemeshko
- IST Austria (Institute of Science and Technology Austria) Am Campus 1 3400 Klosterneuburg Austria
- Kavli Institute for Theoretical Physics University of California Santa Barbara CA 93106 USA
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11
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Kaufmann M, Leicht D, Havenith M, Broderick BM, Douberly GE. Infrared Spectroscopy of the Tropyl Radical in Helium Droplets. J Phys Chem A 2016; 120:6768-73. [PMID: 27531683 DOI: 10.1021/acs.jpca.6b06522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matin Kaufmann
- Department of Physical Chemistry II, Ruhr-University Bochum , 44801 Bochum, Germany
| | - Daniel Leicht
- Department of Physical Chemistry II, Ruhr-University Bochum , 44801 Bochum, Germany
| | - Martina Havenith
- Department of Physical Chemistry II, Ruhr-University Bochum , 44801 Bochum, Germany
| | - Bernadette M Broderick
- Department of Chemistry, University of Georgia , Athens, Georgia 30602-2556, United States
| | - Gary E Douberly
- Department of Chemistry, University of Georgia , Athens, Georgia 30602-2556, United States
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12
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Moradi CP, Xie C, Kaufmann M, Guo H, Douberly GE. Two-center three-electron bonding in ClNH3 revealed via helium droplet infrared laser Stark spectroscopy: Entrance channel complex along the Cl + NH3 → ClNH2 + H reaction. J Chem Phys 2016; 144:164301. [DOI: 10.1063/1.4947089] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Changjian Xie
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Matin Kaufmann
- Department of Physical Chemistry II, Ruhr-University Bochum, D-44801 Bochum, Germany
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA
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13
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Schwan R, Kaufmann M, Leicht D, Schwaab G, Havenith M. Infrared spectroscopy of the ν2 band of the water monomer and small water clusters (H2O)n=2,3,4 in helium droplets. Phys Chem Chem Phys 2016; 18:24063-9. [DOI: 10.1039/c6cp04333j] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Ro-vibrational transitions of water and water clusters (H2O)n=1,2,3,4 for the ν2 bending vibration were observed and assigned to distinct structures.
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14
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Chen L, Zhang J, Freund WM, Kong W. Effect of kinetic energy on the doping efficiency of cesium cations into superfluid helium droplets. J Chem Phys 2015; 143:044310. [PMID: 26233132 PMCID: PMC4522010 DOI: 10.1063/1.4927471] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 07/15/2015] [Indexed: 11/14/2022] Open
Abstract
We present an experimental investigation of the effect of kinetic energy on the ion doping efficiency of superfluid helium droplets using cesium cations from a thermionic emission source. The kinetic energy of Cs(+) is controlled by the bias voltage of a collection grid collinearly arranged with the droplet beam. Efficient doping from ions with kinetic energies from 20 eV up to 480 V has been observed in different sized helium droplets. The relative ion doping efficiency is determined by both the kinetic energy of the ions and the average size of the droplet beam. At a fixed source temperature, the number of doped droplets increases with increasing grid voltage, while the relative ion doping efficiency decreases. This result implies that not all ions are captured upon encountering with a sufficiently large droplet, a deviation from the near unity doping efficiency for closed shell neutral molecules. We propose that this drop in ion doping efficiency with kinetic energy is related to the limited deceleration rate inside a helium droplet. When the source temperature changes from 14 K to 17 K, the relative ion doping efficiency decreases rapidly, perhaps due to the lack of viable sized droplets. The size distribution of the Cs(+)-doped droplet beam can be measured by deflection and by energy filtering. The observed doped droplet size is about 5 × 10(6) helium atoms when the source temperature is between 14 K and 17 K.
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Affiliation(s)
- Lei Chen
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - William M Freund
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
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15
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Hernandez FJ, Brice JT, Leavitt CM, Pino GA, Douberly GE. Infrared Spectroscopy of OH··CH3OH: Hydrogen-Bonded Intermediate Along the Hydrogen Abstraction Reaction Path. J Phys Chem A 2015; 119:8125-32. [DOI: 10.1021/acs.jpca.5b04875] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Federico J. Hernandez
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
- INFIQC,
Dpto. de Fisicoquímica, Facultad de Ciencias Químicas,
Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón. X5000HUA Córdoba, Argentina
| | - Joseph T. Brice
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | | | - Gustavo A. Pino
- INFIQC,
Dpto. de Fisicoquímica, Facultad de Ciencias Químicas,
Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón. X5000HUA Córdoba, Argentina
| | - Gary E. Douberly
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
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16
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Broderick BM, McCaslin L, Moradi CP, Stanton JF, Douberly GE. Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene. J Chem Phys 2015; 142:144309. [DOI: 10.1063/1.4917421] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
| | - Laura McCaslin
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | | | - John F. Stanton
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA
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17
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Raston PL, Douberly GE, Jäger W. Single and double resonance spectroscopy of methanol embedded in superfluid helium nanodroplets. J Chem Phys 2014; 141:044301. [DOI: 10.1063/1.4887348] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Leavitt CM, Moradi CP, Stanton JF, Douberly GE. Communication: Helium nanodroplet isolation and rovibrational spectroscopy of hydroxymethylene. J Chem Phys 2014; 140:171102. [DOI: 10.1063/1.4874850] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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