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Title: Rotational relaxation in molecular hydrogen and deuterium: Theory versus acoustic experiments

Abstract

An explicit formulation of the rotational relaxation time in terms of state-to-state rate coefficients associated to inelastic collisions is reported. The state-to-state rates needed for the detailed interpretation of relaxation in H{sub 2} and D{sub 2}, including isotopic variant mixtures, have been calculated by solving the close-coupling Schrödinger equations using the H{sub 2}–H{sub 2} potential energy surface by Diep and Johnson [J. Chem. Phys. 112, 4465 (2000)]. Relaxation related quantities (rotational effective cross section, bulk viscosity, relaxation time, and collision number) calculated from first principles agree reasonably well with acoustic absorption experimental data on H{sub 2} and D{sub 2} between 30 and 293 K. This result confirms at once the proposed formulation, and the validation of the H{sub 2}–H{sub 2} potential energy surface employed, since no approximations have been introduced in the dynamics. Accordingly, the state-to-state rates derived from Diep and Johnson potential energy surface appear to be overestimated by up to 10% for H{sub 2}, and up to 30% for D{sub 2} at T = 300 K, showing a better agreement at lower temperatures.

Authors:
 [1];  [2]
  1. Laboratory of Molecular Fluid Dynamics @ Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain)
  2. Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States)
Publication Date:
OSTI Identifier:
22308403
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 141; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; COLLISIONS; CROSS SECTIONS; DEUTERIUM; HYDROGEN; MIXTURES; POTENTIAL ENERGY; RELAXATION TIME; SCHROEDINGER EQUATION; SURFACES

Citation Formats

Montero, S., E-mail: emsalvador@iem.cfmac.csic.es, and Pérez-Ríos, J. Rotational relaxation in molecular hydrogen and deuterium: Theory versus acoustic experiments. United States: N. p., 2014. Web. doi:10.1063/1.4895398.
Montero, S., E-mail: emsalvador@iem.cfmac.csic.es, & Pérez-Ríos, J. Rotational relaxation in molecular hydrogen and deuterium: Theory versus acoustic experiments. United States. doi:10.1063/1.4895398.
Montero, S., E-mail: emsalvador@iem.cfmac.csic.es, and Pérez-Ríos, J. Sun . "Rotational relaxation in molecular hydrogen and deuterium: Theory versus acoustic experiments". United States. doi:10.1063/1.4895398.
@article{osti_22308403,
title = {Rotational relaxation in molecular hydrogen and deuterium: Theory versus acoustic experiments},
author = {Montero, S., E-mail: emsalvador@iem.cfmac.csic.es and Pérez-Ríos, J.},
abstractNote = {An explicit formulation of the rotational relaxation time in terms of state-to-state rate coefficients associated to inelastic collisions is reported. The state-to-state rates needed for the detailed interpretation of relaxation in H{sub 2} and D{sub 2}, including isotopic variant mixtures, have been calculated by solving the close-coupling Schrödinger equations using the H{sub 2}–H{sub 2} potential energy surface by Diep and Johnson [J. Chem. Phys. 112, 4465 (2000)]. Relaxation related quantities (rotational effective cross section, bulk viscosity, relaxation time, and collision number) calculated from first principles agree reasonably well with acoustic absorption experimental data on H{sub 2} and D{sub 2} between 30 and 293 K. This result confirms at once the proposed formulation, and the validation of the H{sub 2}–H{sub 2} potential energy surface employed, since no approximations have been introduced in the dynamics. Accordingly, the state-to-state rates derived from Diep and Johnson potential energy surface appear to be overestimated by up to 10% for H{sub 2}, and up to 30% for D{sub 2} at T = 300 K, showing a better agreement at lower temperatures.},
doi = {10.1063/1.4895398},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 11,
volume = 141,
place = {United States},
year = {2014},
month = {9}
}