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Title: Quantum scattering of OH(X{sup 2}{pi}) with He({sup 1}S): Propensity features in rotational relaxation at ultralow energies

Abstract

The collisional relaxation of rotationally ''hot'' OH molecules in He as a buffer gas has been studied as a fully quantum event using an ab initio potential energy surface and the exact dynamical coupling of the relevant angular momenta during the process. The range of energies considered corresponds to the ultralow temperatures of cold traps and the calculations were carried out down to the Wigner regime of cross section behavior. It is shown that the general dependence of the inelastic processes on rotational angular momentum and parity clearly indicates a fairly marked size dependence of the final cross sections on the specific fine structure levels in which the target radical is being prepared to undergo relaxation.

Authors:
; ;  [1]
  1. Department of Chemistry and CNISM, University of Rome, 'La Sapienza', Piazzale A. Moro 5, 00185, Rome (Italy)
Publication Date:
OSTI Identifier:
20974574
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 73; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevA.73.022703; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ANGULAR MOMENTUM; ATOM-MOLECULE COLLISIONS; ATOMS; COLD TRAPS; COUPLING; CROSS SECTIONS; ENERGY TRANSFER; FINE STRUCTURE; HELIUM; MOLECULES; OXYGEN COMPOUNDS; POTENTIAL ENERGY; RELAXATION; SCATTERING; SURFACES; TEMPERATURE RANGE 0000-0013 K

Citation Formats

Gonzalez-Sanchez, L., Bodo, E., and Gianturco, F. A. Quantum scattering of OH(X{sup 2}{pi}) with He({sup 1}S): Propensity features in rotational relaxation at ultralow energies. United States: N. p., 2006. Web. doi:10.1103/PHYSREVA.73.022703.
Gonzalez-Sanchez, L., Bodo, E., & Gianturco, F. A. Quantum scattering of OH(X{sup 2}{pi}) with He({sup 1}S): Propensity features in rotational relaxation at ultralow energies. United States. doi:10.1103/PHYSREVA.73.022703.
Gonzalez-Sanchez, L., Bodo, E., and Gianturco, F. A. Wed . "Quantum scattering of OH(X{sup 2}{pi}) with He({sup 1}S): Propensity features in rotational relaxation at ultralow energies". United States. doi:10.1103/PHYSREVA.73.022703.
@article{osti_20974574,
title = {Quantum scattering of OH(X{sup 2}{pi}) with He({sup 1}S): Propensity features in rotational relaxation at ultralow energies},
author = {Gonzalez-Sanchez, L. and Bodo, E. and Gianturco, F. A.},
abstractNote = {The collisional relaxation of rotationally ''hot'' OH molecules in He as a buffer gas has been studied as a fully quantum event using an ab initio potential energy surface and the exact dynamical coupling of the relevant angular momenta during the process. The range of energies considered corresponds to the ultralow temperatures of cold traps and the calculations were carried out down to the Wigner regime of cross section behavior. It is shown that the general dependence of the inelastic processes on rotational angular momentum and parity clearly indicates a fairly marked size dependence of the final cross sections on the specific fine structure levels in which the target radical is being prepared to undergo relaxation.},
doi = {10.1103/PHYSREVA.73.022703},
journal = {Physical Review. A},
number = 2,
volume = 73,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}
  • Ab initio potential curves of HeO and potential energy surfaces of HeOH for the first three states are presented. The potential surfaces are found to be repulsive with the following topographical characteristics: (1) The minimum energy approach of He to hydroxyl radical is across the angles of 45/sup 0/ and 135/sup 0/. (2) There is not strong coupling between the bond length of OH and the distance of He from the center of mass of the diatom, R. (3) There is a surface crossing between the /sup 2/Pi and /sup 2/..sigma../sup +/ state as He collinearly approaches the O atommore » of OH at R = 2.3 a/sub 0/ and at 2.0 eV above the dissociation limit, He + OH(A/sup 2/..sigma../sup +/). An analytical potential function is produced for the excited ..sigma.. state.« less
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