Shape Resonance Phenomena in CO FollowingK-Shell Photoexcitation

Abstract

Electron cross sections and asymmetries following photoexcitation of the CO $K$ shells were measured directly. Energy analysis of ejected electrons yielded cross sections exhibiting $\sigma$ shape resonances in the $\mathrm{C}\mathrm{}\left(1s\right)\mathrm{}$, $\mathrm{C}\mathrm{}\left(\mathrm{KVV}\right)\mathrm{}$, and $\mathrm{O}\mathrm{}\left(1s\right)\mathrm{}$ channels, and a $\pi$ resonance in the $\mathrm{C}\mathrm{}\left(\mathrm{KVV}\right)\mathrm{}$ channel, confirming earlier indirect measurements. Asymmetry measurements showed a $\sigma$ shape resonance in the $\mathrm{C}\mathrm{}\left(1s\right)\mathrm{}$ channel, in good agreement with the predictions of Dehmer and Dill. The $\mathrm{C}\mathrm{}\left(\mathrm{KVV}\right)\mathrm{}$ $\pi$ resonance showed nearly isotropic behavior.