Ionization of Xenon Rydberg Atoms at a Surface
Abstract
The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a Au(111) surface is being studied. The data show that, despite very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This disagrees with the predictions of hydrogenic theory, which suggests that the ionization distances should be very different. This apparent discrepancy is explained, with the aid of complex scaling calculations, in terms of perturbations in the energies and structure of the atomic states induced by the presence of the surface. These result in energy level shifts and in the appearance of avoided crossings between states in adjacent n-manifolds. As an excited atom approaches the surface it undergoes a series of avoided crossings, which results in the electron probability density oscillating between being oriented toward the surface and toward vacuum. Thus, on average, the electron probability densities associated with the extreme red and blue members of adjacent Stark manifolds are similar, leading to ionization at similar atom/surface separations. Research supported by the NSF and the Robert A. Welch Foundation.
- Publication:
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APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts
- Pub Date:
- May 2003
- Bibcode:
- 2003APS..DMP.J1137D