High-resolution infrared study of the ν1 and ν3 bands, and the equilibrium structure of AsD3

The infrared spectrum of the AsD₃ molecule has been measured in the region of the stretching fundamental bands on a Fourier transform spectrometer with a resolution of 0.0027 cm^-1 and analyzed for the first time. More than 3300 normally allowed and in addition more than 900 forbidden, but perturbation-allowed transitions with J_max ^upper=28 have been assigned to the bands ν₁ and ν₃. An effective Hamiltonian was used which takes into account the resonance interactions between the states (1000) and (0010). A set of 50 (26 diagonal and 24 resonance) refined spectroscopic parameters was obtained from the fit which reproduces the 1229 initial 'experimental' upper state ro-vibrational energies with an rms deviation of 0.00024 cm^-1. The transition moment ratio |μ₁:μ₃| was determined to be 1.2±0.05, and the intensity perturbation μ₁ ξ₁₃ ^y μ₃ found to be negative. The equilibrium values of the bond length r_As-D ^e=1.51130(11) A and interbond angle α_D-As-D ^e=92.0775(40)̊ were determined from the values of the rotational parameters of the ground state and the four fundamental bands.