RESUMEN
The test of an interaction potential for HF-argon recently determined from the spectroscopy of the Van der Waals complex requires accurate experimental widths and shifts cross sections. Since inconsistencies existed between previous measurements, collisional lineshapes were studied at T = 296 K by high-resolution Fourier transform spectroscopy for the 0-0, 0-1, and 0-2 bands. The accurate close-coupling molecular scattering calculations of Green and Hutson (1994. J. Chem. Phys. 100, 891) were extended to a complementary set of kinetic energies in order to check the thermal averaging procedure. Agreement between measured and computed room temperature cross sections is excellent for the three vibrational bands. This confirms the accuracy of the HF-argon surface and particularly its dependence on the HF vibrational level, which is sensitively probed both by the widths and by the shifts cross sections at high j(i) values. Copyright 1999 Academic Press.
RESUMEN
He-broadening coefficients are measured for 28 lines of 12CH3F in the RQ0 (Ki = 0, DeltaK = 1, DeltaJ = 0) and RQ6 (Ki = 6, DeltaK = 1, DeltaJ = 0) branches of the nu6 band, using a tunable diode laser spectrometer. The collisional widths obtained by fitting Rautian profiles to the measured shapes of the lines are slightly larger than those derived from Voigt profiles. The broadening coefficients for the lines belonging to the same low J transitions are significantly greater in the RQ0 branch than in the RQ6 branch. Moreover, they decrease on the whole with increasing J in the RQ0 branch and tend to increase from J varying from 7 to 10 in the RQ6 branch. These trends may be approximately reproduced by calculations based on a semiclassical impact theory of collisional broadening. Copyright 1997 Academic Press. Copyright 1997Academic Press