Comprehensive study of the pentad bending triad region of germane: Positions, strengths, widths and shifts of lines in the 2ν₂, ν₂+ν₄ and 2ν₄ bands of ⁷⁰GeH₄, ⁷²GeH₄, ⁷³GeH₄, ⁷⁴GeH₄, ⁷⁶GeH₄

The high resolution infrared spectra of GeH₄ in its natural abundance were recorded with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm⁻¹ and analyzed in the region of 1400–2000 cm⁻¹ where the first bending overtone 2ν₂, 2ν₄ and combinational ν₂+ν₄ bands are located. Ro–vibrational line positions and energies of the ⁷⁰GeH₄ species were analysed for the first time and line positions and energies of the ⁷²GeH₄ and ⁷⁴GeH₄ species were improved considerably in comparison with the preceding studies. The numbers of 2316/2406/873/3007/2257 transitions with J^max = 21/23/18/22/19 of the 2ν₂ (A₁− and E−type sub–bands), 2ν₄ (A₁−, E− and F₂−type sub–bands) and ν₂+ν₄ (F₁− and F₂−type sub–bands) bands of the ⁷⁰GeH₄, ⁷²GeH₄, ⁷³GeH₄, ⁷⁴GeH₄, and ⁷⁶GeH₄ molecules were used in the joint weighted fit of experimentally assigned transitions with the Hamiltonian model which takes the resonance interactions between the seven, (0200,A₁), (0200,E), (0101,F₁), (0101,F₂), (0002,A₁), (0002,E) and (0002,F₂), vibrational states into account. From our preceding studies 5563 hot band transitions were also taken into account. As the result of a joint fit, a set of 129 fitted parameters was obtained which reproduce the initial 16422 experimental (including “hot”) transitions of five isotopologues with the d_rms=3.26×10⁻⁴ cm⁻¹. A line strength analysis of the 1697 experimentally recorded transitions of all species was made by the fit of their line shapes with the Hartmann-Tran profile and 13 effective dipole moment parameters were obtained from the weighted fit which reproduce the initial experimental line strengths with the d_rms=3.4%. Self–broadening coefficients of 993 lines and self–shift coefficients of 674 lines were determined from the multi–spectrum analysis of these lines.