High resolution study of strongly interacting 2ν1(A1)/ν1+ν3(F2) bands of MGeH4 (M=76,74)

The infrared spectra of GeH4 (88.1 % of 76GeH4, 11.5 % of 74GeH4, and a minor amounts of three other stable isotopic species in the sample) were measured in the 4000-4250 cm−1 region with a high resolution of 0.003 cm−1 at different pressures with the Bruker IFS 125HR Fourier transform interferometer (Nizhny Novgorod, Russia) and were analyzed theoretically. The 1974 transitions with Jmax. = 21 were assigned to the bands ν1+ν3(F2) and 2ν1(A1) of the 76GeH4 isotopologue. Rotational, centrifugal distortion, tetrahedral splitting, and interaction parameters for the (1010, F2) and (2000, A1) vibrational states were determined from the fit of experimental line positions. Influence of the (0020, A1), (0020, E) and (0020, F2) vibrational states on the structure of the states (1010, F2) and (2000, A1) is taken into account. In this case, the main resonance interaction parameters have been estimated on the basis of the local mode model and then fitted. A set of spectroscopic parameters of the effective Hamiltonian obtained from a weighted fit reproduces the initial experimental data with the drms=4.5×10−4 cm−1. The results of analogous analysis of the 74GeH4 isotopologue (the number of assigned transitions is 652) are presented also.