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Title: Rotational Dynamics of the Methyl Radical in Superfluid 4He Nanodroplets

Abstract

Here, we report the ro-vibrational spectrum of the ν 3(e') band of the methyl radical (CH 3) solvated in superfluid 4He nanodroplets. Five allowed transitions produce population in the N K = 0 0, 1 1, 1 0, 2 2 and 2 0 rotational levels. The observed transitions exhibit variable Lorentzian line shapes, consistent with state specific homogeneous broadening effects. Population relaxation of the 00 and 11 levels is only allowed through vibrationally inelastic decay channels, and the PP 1(1) and RR 0(0) transitions accessing these levels have 4.12(1) and 4.66(1) GHz full-width at half-maximum line widths, respectively. The line widths of the PR 1(1) and RR 1(1) transitions are comparatively broader (8.6(1) and 57.0(6) GHz, respectively), consistent with rotational relaxation of the 2 0 and 2 2 levels within the vibrationally excited manifold. The nuclear spin symmetry allowed rotational relaxation channel for the excited 1 0 level has an energy difference similar to those associated with the 2 0 and 2 2 levels. However, the PQ 1(1) transition that accesses the 1 0 level is 2.3 and 15.1 times narrower than the PR 1(1) and RR 1(1) lines, respectively. The relative line widths of these transitions are rationalized inmore » terms of the anisotropy in the He-CH 3 potential energy surface, which couples the molecule rotation to the collective modes of the droplet.« less

Authors:
 [1];  [1]; ORCiD logo [1]
  1. Univ. of Georgia, Athens, GA (United States)
Publication Date:
Research Org.:
Univ. of Georgia Research Foundation, Athens, GA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1409048
Grant/Contract Number:  
SC0008086
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 117; Journal Issue: 46; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Morrison, Alexander M., Raston, Paul L., and Douberly, Gary E. Rotational Dynamics of the Methyl Radical in Superfluid 4He Nanodroplets. United States: N. p., 2012. Web. doi:10.1021/jp310083j.
Morrison, Alexander M., Raston, Paul L., & Douberly, Gary E. Rotational Dynamics of the Methyl Radical in Superfluid 4He Nanodroplets. United States. doi:10.1021/jp310083j.
Morrison, Alexander M., Raston, Paul L., and Douberly, Gary E. Fri . "Rotational Dynamics of the Methyl Radical in Superfluid 4He Nanodroplets". United States. doi:10.1021/jp310083j. https://www.osti.gov/servlets/purl/1409048.
@article{osti_1409048,
title = {Rotational Dynamics of the Methyl Radical in Superfluid 4He Nanodroplets},
author = {Morrison, Alexander M. and Raston, Paul L. and Douberly, Gary E.},
abstractNote = {Here, we report the ro-vibrational spectrum of the ν3(e') band of the methyl radical (CH3) solvated in superfluid 4He nanodroplets. Five allowed transitions produce population in the NK = 00, 11, 10, 22 and 20 rotational levels. The observed transitions exhibit variable Lorentzian line shapes, consistent with state specific homogeneous broadening effects. Population relaxation of the 00 and 11 levels is only allowed through vibrationally inelastic decay channels, and the PP1(1) and RR0(0) transitions accessing these levels have 4.12(1) and 4.66(1) GHz full-width at half-maximum line widths, respectively. The line widths of the PR1(1) and RR1(1) transitions are comparatively broader (8.6(1) and 57.0(6) GHz, respectively), consistent with rotational relaxation of the 20 and 22 levels within the vibrationally excited manifold. The nuclear spin symmetry allowed rotational relaxation channel for the excited 10 level has an energy difference similar to those associated with the 20 and 22 levels. However, the PQ1(1) transition that accesses the 10 level is 2.3 and 15.1 times narrower than the PR1(1) and RR1(1) lines, respectively. The relative line widths of these transitions are rationalized in terms of the anisotropy in the He-CH3 potential energy surface, which couples the molecule rotation to the collective modes of the droplet.},
doi = {10.1021/jp310083j},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 46,
volume = 117,
place = {United States},
year = {2012},
month = {12}
}

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