Spectroscopy and dynamics of vibrationally autoionizing nitric oxide Rydberg states

Vibrationally autoionizing Rydberg states of nitric oxide are studied to learn about the dynamics of this nonadiabatic (Born-Oppenheimer violating) process. Most of chemical physics is described in terms of the Born-Oppenheimer approximation, in which the nuclei are assumed to be moving too slowly to interact with the motion of the electrons. This thesis presents the study of a specific case where this approximation breaks down.; A new theoretical development based on multichannel quantum defect theory (MQDT) is derived, demonstrating the energy dependence of photoelectron dynamics through a weakly autoionizing Rydberg state. This model of resonance mediated photoionization is compared to a first order perturbation theory model of bound-continuum mixing. The two models are shown to predict equivalent results for angular distribution measurements from optically prepared, weakly autoionizing Rydberg states with minimal contribution from direct photoionization.; Spectra are reported for Rydberg states converging to the NO+ X (v+ = 1) with total angular momentum, N, from 19–27, and principal quantum number, n, from 11–18. The spectra were recorded by measuring ion current produced by vibrational autoionization of the prepared states. Spectral features were identified by a combination of techniques, including simulations and circular dichroism. Resonant energies were fit to an MQDT expression using a nonlinear least-squares algorithm to extract phase shift parameters of closed-channel K matrix for s, p, and d channels. Eigen defects deduced from this fit are reported for the (v = 1) μ_sd1σ, μ _sd2σ, μ_{d π}, μ_dδ, μ _pσ, and μ_{p π} channels.; Time-of-flight photoelectron spectra and photoelectron angular distributions are reported for seven Rydberg states in the NO (v = 1) s–d complex. A previously reported analysis of the 14 s(v = 1, R = 20) Rydberg state is corrected, and the conclusions from that report are re-evaluated. Significant λ mixing resulting from vibrational autoionization is confirmed, indicating significant contribution from long-range coupling between the bound states and the continuum.