Inverse-photoemission observation of the shape resonance

Abstract
We present the first observation to our knowledge of the molecular shape resonance in adsorbed CO using the technique of inverse photoemission. By comparison with earlier photoionization measurements we are able to examine the role of the final-state potential in determining the binding energy of the shape resonance. We find that screening of the photohole is more effective for valence-band photoionization than for the more localized core-level photoionization.