RYDBERG-VALENCE PERTURBATIONS AND DISSOCIATIVE PATHWAYS IN NO

Abstract

We will report on the results of laser spectroscopic studies of NO in the region around 8.55cv $(69000 cm^{-1})$. In this region there are numerous perturbations between low n Rydberg and valence states. We have studied the $K {^{2}}\Pi (\nu =2)$ state at high resolution using optical-optical double resonance with continuous wave lasers. We have observed a complicated dependence of the linewidths as a function J suggesting that the K state is predissociated by a mechanism which involves interaction with several electronic states. It is known that the $K {^{2}}\Pi (\nu =2)$ state is perturbed by the $B {^{2}}\Pi (\nu=29)$ valence state. From data on the $B (\nu =29)$ state published by Cheung et al. we have deperturbed the K and B states. Gallusser and Dressler have performed a multi-state deperturbation of five ${^{2}}\Pi$ states over many vibrational levels which includes this energy region. They concluded that the $K (\nu=2)$ state interacts primarily with the $B (\nu=29)$ state. The molecular constants obtained from our fit are very close to those obtained by Gallusser and Dressler indicating that this is primarily a two state interaction. However, there are still relatively large and systematic differences between observed and calculated energies of the B state indicating that couplings with still other electronic states need to be considered. Perturbations, due to the spin-orbit and rotation operators, with electronic states not included in the multi-state deperturbation must be responsible for the observed predissociation. They may also be responsible, in part, for the difficulty in fitting the B state. We will discuss the possible dissociative pathways responsible for the observed linewidths and the connection to the additional perturbations observed in the B state.