Ionization of Xenon Rydberg Atoms at a Metal Surface

Experiments in which a thermal-energy beam of xenon Rydberg atoms is directed at near grazing incidence onto a flat Au(111) surface are described that provide new insight into charge transfer and electron tunneling during atom/surface interactions. Analysis of the data shows that for the present range of principal quantum number n, 13≤n≤20, ionization occurs at an atom/surface separation Zᵢ0ex0ex=0ex0ex(4.5±0.9)n²a₀, where n²a₀ is the Bohr radius of the atom. This result is in good agreement with the value Zᵢ~3.8n²a₀ predicted by ab initio hydrogenic theory.