Long-path infrared spectra of SiH4–Ar, –Kr, and –para-H2 van der Waals complexes in the 2190 cm−1 region

Infrared spectra of SiH4–Ar, SiH4–Kr, and SiH4–para-H2 van der Waals molecules are observed in the region of the ν4 fundamental band of silane by means of long-path (84–180 m), low temperature (95 K) equilibrium gas cell FTIR spectroscopy. The observed spectral features mostly correspond to unresolved Q-branches. For SiH4–Ar, some of these features are the same as those previously analyzed at high-resolution in a supersonic jet study by Randall et al. [J. Chem. Phys. 100 (1994) 7051], while others are higher K-value transitions that were not populated in the jet. The positions of these new transitions can be predicted very well by the parameters of Randall et al. For SiH4–Kr, which has not been studied previously, 15 Q-branch feature are assigned and fitted to obtain a preliminary set of parameters. For SiH4–para-H2 a single prominent feature is observed and assigned as the RQ0(J) branch with A symmetry correlating with the SiH4 monomer R(0) transition. The SiH4–Kr and SiH4–para-H2 results should be useful as a basis for future high-resolution studies of these complexes.