5314027792

POSTER SESSION, H6

COLLISIONAL BROADENING COEFFICIENTS IN THE i/₆ BAND OF CH₃F PERTURBED BY RARE GASES (Ar, He).

M URI EL LEPERE,GHISLAIN BLANQUET,J ACQUES WALRAND, Laboratoire de Spectroscopie Moleculairc, Facultes Universitaires Notre-Dame de la Paix, 61, rue de Bruzelles, B-5000 Namur, Belgium; JEAN-PIERRE BOUANICH. Laboratoire de Physiąue Moleculairc et Applications, CNRS, Universite de Paris-Sud, Bdtiment 350, F-91Ą05 Orsay cedei, France.

Ar- and He-broadening coefficients are measured for several lines of CH3F in the ^RQo and ^rQ$ branches of the v§ band, using a tunable diode-laser spectrometer. These lines with J values ranging from 1 to 29 in the ^rQq branch (AK = 1, AJ = 0, K_x = 0) and from 7 to 22 in the ^RQ₆ branch (AA' = 1, AJ = 0, K_x = 6) are respectively located near 1183 crn~^l and 1217 cm"¹. The collisional widths obtained by fitting Rautian profiles to the measured shapes of the lines are significantly larger, especially for the overlapping lines at Iow J values, than those obtained from Voigt profiles. The broadening coefficients for the lines belonging to the same Iow J transitions (J =7-10) are significantly greater in the ^rQo branch than in the ^rQg branch for He, and only slightly greater for Ar. These trends are approximately reproduced by calculations based on a semi-classical impact model including adjustable potential parameters.