High resolution FTIR study of the ν5 bands of HSID3 and H120SnD3

High resolution Fourier Transform spectra of HSiD3 and monoisotopic (HSnD3)-Sn-120 have been recorded in the region of the v(5) fundamental at 850.68 and 646.90 cm(-1) with a resolution of 3.3 and 2.8 x 10(-3) cm(-1), respectively. About 2000 rovibrational transitions of each species have been assigned and fitted to two different reductions of the effective Hamiltonian, with sigma(Fit) = 1.2 x 10(-4) (HSiD3) and 1.4 x 10(-4) cm(-1) ((HSnD3)-Sn-120). The two sets of parameters were shown to be equivalent, and relations between parameters belonging to different reductions are perfectly fulfilled. Furthermore the ground state constants C-0 and D-K0 have been determined for the first time. For consistency the previously measured data belonging to the v(5) band of (HGeD3)-Ge-70 have been refitted, sigma(Fit) = 1.6 x 10(-4) cm(-1), on the basis of improved ground state parameters including the h'(3) term accounting for the splitting of the K = 3 level. (C) 1998 Academic Press.