QUANTUM SCATTERING STUDIES OF VIBRATIONAL-EXCITATION IN COLLISIONS OFNO(X 2-PI) WITH A AG(111) SURFACE

We report the results of fully quantum close-coupled studies of vibrat ional excitation in collisions of NO (X 2PI) With a Ag (111) surface. The interaction potentials used were an extension, to include the depe ndence on the NO bond distance, of the recent corrected effective medi um potential energy surfaces (PES) of Depristo and Alexander. [J. Chem . Phys. 94, 8454 (1991)]. The final state rotational distributions sho w evidence of at least four rotational rainbows, corresponding to scat tering on (and interference between) the two PES which arise when the degeneracy of the NO molecule is lifted upon approach to the surface. A strong tendency is seen to populate the lower spin-orbit manifold at low to moderate final J, which disappears as J rises beyond 30.5 and the final states are better described in Hund's case (b). Simultaneous ly, there exists a propensity to populate those A-doublet levels in wh ich the electronic-rotational wave function is symmetric (PI(A')) with respect to reflection of the electronic coordinates in the plane of r otation of the scattered NO molecule. This feature is similar to what has been seen experimentally.