High resolution infrared spectra of the ν1-ν4 bands of BiH3, and ab initio calculations of the spectroscopic parameters

The infrared spectrum of short-lived BiH3 has been studied by Fourier transform technique. The BiH stretching bands v(1)/v(3) at 1733.2546/1734.4671 cm(-1) and the bending fundamentals v(2)/v(4) at 726.6992/751.2385 cm(-1) have been measured with a resolution of 5.5 and 6.6 x 10(-3) cm(-1), respectively. The spectra were analyzed using different reductions of the rovibrational Hamiltonian accounting for the numerous resonance interactions in particular within the strongly Coriolis-coupled bending dyad. About 1150 and 980 transitions belonging to the v(1)/v(3) and v(2)/v(4) bands were fitted with an rms deviation of 0.62 and 0.53 x 10(-3) cm(-1), respectively. High-level ab initio calculations at the coupled cluster CCSD(T) level with an energy-consistent small-core pseudopotential and large basis sets were carried out to determine the equilibrium structure, the anharmonic force field, and the associated spectroscopic constants of BiH3. The theoretical results are in good agreement with the available experimental data. (C) 2004 Elsevier Inc. All rights reserved.