15min:
SPECTROSCOPY, DISSOCIATION DYNAMICS AND POTENTIAL ENERGY SURFACES FOR CN(A)-Ar.

JIANDE HAN AND MICHAEL C. HEAVEN, Department of Chemistry, Emory University, Atlanta, GA 30322; UDO SCHNUPF, Department of Agriculture, ARS/NCAUR/PPL, Peoria, IL 61604.

The A2 Pi-X2 Sigma+ band system of CN-Ar has been examined using fluorescence depletion and action spectroscopy techniques. Eight vibronic bands of the complex were observed in association with the monomer 3-0 transition. Pump-probe measurements were used to characterize CN(A2 Pi3/2, v=3) fragments from direct photodissociation of CN(A2 Pi, v=3)-Ar, and CN(X2 Sigma+, v=7) fragments from CN(A2 Pi, v=3)-Ar predissociation. The latter showed a marked preference for population of positive parity diatomic rotational levels. Bound state calculations were used to assign the A-X bands, and to obtain fitted potential energy surfaces for the A state. The average potential obtained from fitting had a well depth of De=137.8 cm-1. High-level ab initio calculations were used to obtain equilibrium Jacobi coordinates of thetae=94\circ and Re=7.25 bohr. The near symmetric character of the fitted potential energy surface was consistent with the symmetry preference observed in the predissociation dynamics.