First high–resolution analysis of the 2ν₁(A₁) and ν₁+ν₃(F₂) interacting states of ⁷²GeH₄ and ⁷³GeH₄

The spectra of germane ⁷²GeH₄ and ⁷³GeH₄ enriched up to 99.9 % were recorded with high resolution (0.003 cm⁻¹) at different pressures with the Bruker IFS 125HR Fourier transform spectrometer (Nizhny Novgorod, Russia). The region of 4020–4260 cm⁻¹, where the 2ν₁(A₁) and ν₁+ν₃(F₂) bands are located, was theoretically analyzed. The 2025 and 1774 transitions with J^max=21 were assigned to these bands of the ⁷²GeH₄ and ⁷³GeH₄ species. Rotational, centrifugal distortion, tetrahedral splitting, and interaction parameters of the (2000, A₁) and (1010, F₂) vibrational states were determined from the fit of experimental line positions of both isotopologues. The obtained sets of 13/13 fitted parameters reproduce the initial 2025/1774 experimental line positions with a d_rms=2.9×10⁻⁴ cm⁻¹ and d_rms=2.7×10⁻⁴ cm⁻¹ (for ⁷²GeH₄ and ⁷³GeH₄, respectively).