Stuttgart 2012 – scientific programme
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A: Fachverband Atomphysik
A 43: Precision spectroscopy of atoms and ions IV
A 43.7: Talk
Friday, March 16, 2012, 12:00–12:15, V47.03
Van der Waals interaction with a complex surface — Elad Eizner1, Baruch Horovitz1, and •Carsten Henkel2 — 1Ben Gurion University of the Negev, Beer Sheva, Israel — 2Universität Potsdam, Germany
When an atom or molecule approaches a surface, it is subject to a (typically) attractive interaction due to fluctuations in its electric and magnetic dipole moments (London 1930, Casimir and Polder 1948, Lifshitz 1955). We discuss the impact of mobile charges localized at and below the surface on this well-known van der Waals potential. This is relevant, for example, in miniaturized traps (atom chips) and in the scattering of atomic beams. The charges at the surface participate in the screening of the fields due to the molecular dipole. As a result, new regimes and power laws emerge when the surface distance gets comparable to the electronic screening length. We analyze different materials (metals and semiconductors) and suggest that the interaction can be used as a probe of charge transport at the surface. The temperature-dependence of the van der Waals potential is compared to the macroscopic Casimir force between two conducting plates.