Local mode spectroscopic study of the AsH 3 molecule: the perturbed (500) local mode overton

The high resolution Fourier transform spectra of AsH 3 in the region of 9720-9900 cm -1 , which had been recorded at a resolution of 0.015 cm -1 , were assigned to the (500; A 1 ) and (500; E ) local mode overtones and rotationally analyzed. The effective spectroscopic parameters were obtained by nonlinear least-squares fitting the vibration-rotational Hamiltonian with the rotational energy levels up to J =6 (98 levels in all) included. The evolution of the rotational energy patterns from v =1 to v =6 shows that the tendency of normal mode to local mode vibration evolution has been stopped by perturbations in relatively high energy region.