The silane isotopomers 29SiH4 and 30SiH4 constants of the ν2/ν4 dyad

The IR spectrum of two silane isotopomers containing 29Si and 30Si was investigated with CO2 laser side bands in the range between 877 and 954 cm−1 at a resolution of 2 × 10−5 cm−1. An analysis of the ν2 and (or) ν4 dyad has been performed, including data obtained by Henry and Valentin from a Fourier transform spectrum and sub-Doppler lines observed by Borde (Rev. Cethedec-Ondes NS, 83(1), 1 (1983)) and Skrzypczak et al. (J. Mol. Spectrosc. 138, 311 (1989)). From the fit 41 vibration–rotation constants, tΩ(K,nΓ) of the ν2/ν4 Hamiltonian have been determined.