The silane isotopomers (Si-29)H4 and (Si-30)H4 constants of the nu2/nu4 dyad

Silane isotopomers may be of some importance in IR astronomy, since the main isotopomer (with Si-28) has already been discovered in a planetary nebula surrounding the IR star IRC + 10216. With a view toward future isotope investigations of stellar objects, the IR spectrum of two silane isotopomers containing Si-29 and Si-30 is investigated with tunable CO2 laser sidebands in the 877-954-kayser range at a resolution of 0.00002 kayser. An analysis is performed of the nu2 and nu4 dyad, including data by Henry and Valentin (1986) from a Fourier transform spectrum and sub-Doppler lines observed by Borde (1983) and Skrzypczak et al. (1989). Forty-one vibration-rotation constants of the nu2/nu4 Hamiltonian are determined from the spectrum fitting.