High Resolution Angle-and Energy-Resolved Photoelectron Spectroscopy of NO: Partial Wave Decomposition of the Ionization Continuum.

摘要

This reprint reports a two-color high-resolution energy- and angle-resolved study of the photoelectrons produced in the (1+1) REMPI of NO via rotational levels of the A 2 sigma (+) nu=0 state. Markedly different photoelectron angular distributions arise from production of ions in different rotational states (Delta N = 0, + or - 1, + or - 2 transitions in the ionization step). We also observe that Delta N = + or - 2 angular distributions are very sensitive to the intermediate state alignment. A model is put forward in which experimental observables (angle- and energy-resolved photoelectron spectra) are used to determine the attributes (relative amplitudes and phase shifts) of a small number of interfering continuum channels that contribute to the ionization step as well as the fraction of parallel character of the ionization step. Nearly 70% of the ejected photoelectrons are associated with the Delta N = 0 ionization transition; the partial wave composition of these electrons is dominated by p character. The less important Delta N = + or - 1 peaks have both s- and d-wave character. The Delta N = + or - 2 photoelectron peaks exhibit far more f-wave than p-wave character because destructive interference nearly removes the p-wave contribution to the angular distribution. The partial wave decomposition is used to predict angular distributions resulting from excitation of the intermediate state by different rotational branch transitions; these predictions are in excellent agreement with the measured distributions. (jhd)