Ionization of Rydberg H atoms at band-gap metal surfaces via surface and image states

TL;DR

This study uses wavepacket propagation to explore how Rydberg hydrogen atoms interact with copper surfaces, revealing charge transfer enhancements linked to surface and image states, and suggesting a new method to probe surface electronic structures.

Contribution

It provides the first detailed wavepacket analysis of Rydberg atom interactions with copper surfaces, highlighting the role of surface states in charge transfer processes.

Findings

Charge transfer is enhanced at energies near surface and image states.

Overlap of Rydberg and surface orbitals facilitates charge transfer.

Rydberg-surface collisions can probe surface electronic structures.

Abstract

Wavepacket propagation calculations are reported for the interaction of a Rydberg hydrogen atom ($n=2-8)$ with Cu(111) and Cu(100) surfaces (represented by a Chulkov potential), in comparison with a Jellium surface. Both copper surfaces have a projected band gap at the surface in the energy range degenerate with some or all of the Rydberg energies. The charge transfer of the Rydberg electron to the surface is found to be enhanced for $n$ values at which there is a near-degeneracy between the Rydberg energy level and an image state or a surface state of the surface. The enhancement is facilitated by the strong overlap of the surface image-state orbital lying outside the surface and the orbital of the incoming Rydberg atom. These calculations point to the possibility of using Rydberg-surface collisions as a probe of surface electronic structure.