HIGH-RESOLUTION SPECTROSCOPY OF NU-3 AND NU-1+NU-3 BANDS OF SID4

The high-resolution Fourier transform infrared spectra of the v3 fundamental and v1 + v3 stretching combination bands of silane-d4, SiD4, have been recorded and analyzed at a resolution of O.004 cm-1. The molecular constants of the ground state, v3 and v1 + v3 states were derived. No evidence of the vibrational localization was found in the v1 + v3 state, indicating a considerable increase in the inter-bond coupling parameter-lambda due to the deuterium substitution. The calculation shows that the very small inter-bond coupling parameter-lambda of SiH4 is the result of nearly complete cancellation of kinetic and potential couplings, which is no longer the case after deuterium substitution.