First study of the ro-vibrational structure of the g-symmetry vibrational states of C₂D₄ from the analysis of hot bands: The ν₇+ν₁₀−ν₁₀ and ν₁₀+ν₁₂−ν₁₀ bands

The two strongest absorption “hot” bands of C₂D₄, ν₇+ν₁₀−ν₁₀ and ν₁₀+ν₁₂−ν₁₀ were analyzed for the first time on the basis of high resolution infrared spectra recorded with a Bruker high resolution Fourier transform spectrometer. About 740 and 550 transitions (233 and 174 upper state ro-vibrational energy values) with J^max.=25, K_a ^max=18 and J^max.=20, K_a ^max.=10 for the bands ν₇+ν₁₀−ν₁₀ and ν₁₀+ν₁₂−ν₁₀ were assigned. The obtained upper ro-vibrational energies were used then in the weighted fit of parameters of the effective Hamiltonian which takes into account resonance interactions between the vibrational states (v₇=v₁₀=1) and (v₁₀=v₁₂=1), on the one hand, and eight other closely located vibrational states, on the other hand. A set of 46 varied parameters was obtained from the fit, which reproduces the initial experimental data with the rms deviation of 2.5×10⁻⁴cm⁻¹ and which is close to experimental uncertainties.