High-resolution IR spectrum of AsH₂D: Ro-vibrational analysis of the bending triad bands ν₃, ν₄, and ν₆

The infrared spectrum of the AsH₂D molecule has been measured in the region of the three bending fundamental bands on a Fourier transform spectrometer with a resolution of 0.0024 cm^-1 and analyzed for the first time. More than 7500 normally allowed and in addition about 600 forbidden, but perturbation-activated transitions with J^max = 21, K_a^max = 20 and K_c^max = 21 have been assigned to the bands ν₃, ν₄, and ν₆. The measured transition wavenumbers were used to determine 1047 upper energy values. These energies were fitted with a Watson-type Hamiltonian in A reduction and III^l representation taking into account resonance interactions between all three bending states, (001000), (000100), and (000001) and led to a physically meaningful set of 25 diagonal and 52 resonance spectroscopic parameters. These reproduce the experimental energies with an rms deviation of 0.00021 cm^-1, which is close to the experimental uncertainty.