The rotational and vibrational dynamics of argon-methane. II. Experiment and comparison with theory

Presented here is a detailed comparison between the experimental near infra red spectrum of argon-methane and the results of a theoretical calculation based upon the methods described in a companion paper, hereafter referred t o as paper I [T. G. A. Heijmen et al., J. Chem. Phys. 110, 5639 (1999), pre ceding paper]. Many of the bands in the spectrum are easily assigned direct ly from this comparison. The spectrum is shown to be highly sensitive to th e anisotropy of the argon-methane potential surface and the agreement with the ab initio spectrum, although not quantitative, is very good. The predis sociation linewidths observed in the experimental spectra are found to be s trongly dependent upon the symmetry of the excited state. Symmetry consider ations place restrictions on the final rotational states that can be access ed, possibly explaining the differences in the lifetimes. (C) 1999 American Institute of Physics. [S0021-9606(99)01710-9].