THE FAR INFRARED SPECTRUM OF $H_{2}$ AND $H_{2}$ IN MIXTURE WITH He: EXPERIMENT AND $THEORY^{\ast}$
Loading...
Date
1984
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The far infrared spectra of $H_{2}$ and $H_{2}$ in mixtures with He, have been measured at a variety of temperatures from 77K to room temperature and from about $30 cm^{-1}$ to almost $2000 cm^{-1}$ for hydrogen. These spectra have been analyzed with the BC semi-empirical line shape $model,^{1}$ and the various induced dipole components have been resolved. More recently, an exact quantum mechanical formalism of the line shape problem has been $developed.^{2,3}$ Excellent agreement with experimental spectra has been obtained using ab $initio^{4}$ and empirical induced dipole models and modern refined potential functions. These calculations show the importance of dimers and pre-dissociating molecules in the collision-induced spectra of $H_{2}$ even at temperatures as high as 120K, the temperature of Jupiter's upper atmosphere. Finally, from camparisons of the semi-empirical BC model line shape with quantum mechanically computed (QMC) shapes it is shown that the parameters in this model are accurately given by simple relations involving the first three spectral moments. Expensive quantum line shape computations may thus be replaced by the BC model, with parameters derived from relativity simple moment $calculations.^{5}$
Description
$^{\ast}$ Supported by the National Science Foundation, grant AST-8310786. $^{1}$ G. Birnbaum and E.R. Cohen, Canad. J. Phys. 54, 593 (1976). $^{2}$ G. Birnbaum, S.I. Chu, A. Dalgarno, L. Frommhold, E.L. Wright, Phys. Rev. A29, 595 (1984). $^{3}$ G. Birnbaum, B. Guillot, and S. Bratos, Adv. Phys. Chem. 51, 49 (1982). $^{4}$ W. Meyer and J. Schaefer, in press. $^{5}$ A. Borysow, M. Moraldi, L. Frommhold, JQSRT, in press.
Author Institution: Physics Department, University of Texas at Austin; National Bureau of Standards, University of Texas at Austin
Author Institution: Physics Department, University of Texas at Austin; National Bureau of Standards, University of Texas at Austin