Photoelectron Angular Distributions of Rotationally Selected NO Rydberg States

The photoelectron angular distributions from autoionizing $\mathrm{ns}$ and $\mathrm{nf}$ Rydberg states of NO are presented. A striking dependence of the angular distribution on the rotational level in the excited Rydberg complex is observed: The sign of the asymmetry parameter $\beta$ alternates for consecutive rotational levels. A multichannel quantum defect calculation shows qualitative agreement with the experimental results and indicates the role of predissociation in the decay of these Rydberg states.