FTIR study of the second stretching vibrational overtone system of (H3GeD)-Ge-70: Example of an almost asymmetric rotor band

The FTIR spectrum of monoisotopic (H3GeD)-Ge-70 around 6100 cm(-1) was recorded with a resolution of about 0 . 012 cm(-1). A perpendicular-type band, nu(0)(E) = 6129 . 441 cm(-1), is observed, which is unperturbed for K' less than or equal to 12. Its rotational analysis reveals, in addition to rovibrational r and q resonance effects within the E vibrational state, a strong rovibrational alpha resonance perturbation by an almost degenerate perturber of A(1) symmetry, nu(0) = 6129 . 434 cm(-1). Owing to intensity perturbations the parallel component is very weak in spite of a transition moment ratio M(E)/M(A(1)) of about -2. The rovibrational energy level pattern is indicative of local mode behaviour of the upsilon((GeH)) = 3 state, in which Coriolis effects are almost absent and simple arithmetic relations between vibration-rotation parameters fulfilled as expected. This gives rise to an excited state energy level pattern almost consistent with that of an asymmetric rotor.