Abstract
The dynamics of excited electrons in insulator quantum well states on a metal substrate were determined by femtosecond two-photon photoemission for the first time. Lifetimes are reported for the first three excited states for 1–6 atomic layers of Xe on Ag(111). As the image states evolve into quantum well states with increasing coverage, the lifetimes undergo an oscillation as the layer boundary crosses each node of the wave function. The lifetime data are modeled by extending the two-band nearly free-electron approximation to account for the presence of a dielectric layer. The lifetimes are shown to depend on the spatial distribution of the interfacial electron.
- Received 20 June 1997
DOI:https://doi.org/10.1103/PhysRevLett.79.4645
©1997 American Physical Society