Far-infrared absorption by collisionally interacting nitrogen and methane molecules.
Quantum line shape calculations of the rototranslational enhancement spectra of nitrogen-methane gaseous mixtures are reported. The calculations are based on a recent theoretical dipole function for interacting N(2) and CH(4) molecules, which accounts for the long-range induction mechanisms: multipolar inductions and dispersion force-induced dipoles. Multipolar induction alone was often found to approximate the actual dipole surfaces of pairs of interacting linear molecules reasonably well. However, in the case of the N(2)-CH(4) pair, the absorption spectra calculated with such a dipole function still show a substantial intensity defect at the high frequencies (>250 cm(-1)) when compared to existing measurements at temperatures from 126 to 297 K, much as was previously reported.
Buser
Michael
M
Physics Department, University of Texas, Austin, Texas 78712, USA.
Frommhold
Lothar
L
Gustafsson
Magnus
M
Moraldi
Massimo
M
Champagne
Mark H
MH
Hunt
K L C
KL