REFINEMENT OF THE OH A2(SIGMA-ENERGY SURFACE()(V=0)+AR INTERMOLECULARPOTENTIAL)

Several intermolecular vibrational levels of the excited electronic st ate of OH-Ar correlating with OH A 2SIGMA+ (v = 0) + Ar have been char acterized by laser-induced fluorescence and hole-burning experiments. The OH-Ar levels identified include the lowest intermolecular level, a n intermolecular bending level with a lower degree of stretching excit ation than previously observed, and intermolecular levels with two qua nta of bending excitation. The intensities of electronic transitions t o these levels from the lowest intermolecular level of the ground elec tronic state of OH-Ar (X 2PI) are significantly weaker than those of t ransitions previously reported. These data are used to refine a semiem pirical potential for OH A 2SIGMA+ (v = 0) + Ar proposed by Bowman et al. [J. Phys. Chem. 94, 2226 (1990)]. The potential parameters have be en adjusted to increase the potential anisotropy and the steepness of the radial potential in the O-H-Ar well region. The bound states suppo rted by the adjusted potential have been calculated by taking into acc ount the electron spin angular momentum of the OH radical. The calcula ted vibrational energies and rotor constants reproduce the rovibration al structure observed experimentally. A theoretical simulation of the OH-Ar electronic excitation spectrum based on the adjusted intermolecu lar potential yields an intensity pattern which is consistent with exp erimental results.