Carbon K-shell Photo Ionization of CO: Molecular frame angular Distributions of normal and conjugate shakeup Satellites

TL;DR

This study measures the angular distributions of photoelectrons from CO molecules' carbon K-shell, revealing insights into shakeup satellites and resonance phenomena in molecular photoionization.

Contribution

It provides the first detailed molecular frame angular distributions of shakeup satellites in CO, distinguishing shake processes from electron scattering mechanisms.

Findings

Normal b5-satellite lines resemble main photoline distributions

Conjugate shakeup states exhibit similar angular shapes to b5-symmetry states

Presence of b5-shape resonance in all satellite lines

Abstract

We have measured the molecular frame angular distributions of photoelectrons emitted from the Carbon K shell of fixed-in-space CO molecules for the case of simultaneous excitation of the remaining molecular ion. Normal and conjugate shake up states are observed. Photo electrons belonging to normal \Sigma -satellite lines show an angular distribution resembling that observed for the main photoline at the same electron energy. Surprisingly a similar shape is found for conjugate shake up states with \Pi -symmetry. In our data we identify shake rather than electron scattering (PEVE) as the mechanism producing the conjugate lines. The angular distributions clearly show the presence of a \Sigma -shape resonance for all of the satellite lines.