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A: Atomphysik

A 9: Poster I

A 9.8: Poster

Mittwoch, 6. März 2002, 11:00–13:00, Schloss

Quantum Reflection of Neutral Atoms from Surfaces —Experimental Data and an Exact Quantum Mechanical Model — •Viola Druzhinina and Maarten DeKieviet — Physikalisches Institut, Universität Heidelberg

The wave nature of very slow atoms may lead to quantum phenomena, which can become dominant when scattering from solid surfaces [1]. As an example, we have observed quantum specular reflection of helium atoms from a very rough α-Quartz surface at average atom velocities less than 20 m/s.

Whereas the classical turning point is situated at the repulsive wall of the atom - surface potential, for decreasing atom kinetic energies, this quantum mechanically smears out to a No-dqturning regionNo-dqat the potential’s ATTRACTIVE part [2][3]. Quantum reflection thus depends only on the atom’s incoming velocity and the parameters of the attractive part of the potential.

We present a model for calculating the atom wave function and the reflection coefficient, which gives good agreement with both experimental data and other theoretical predictions. In addition, it is shown that surface roughness lowers reflectivity, as a consequence of dephasing of the reflected wave.

[1] Carraro C. and Cole M.W., Z. Phys. B, 98 (1995) 319

[2] Böheim J., Brenig W. and Stutzki J., Phys. Z. B, 48 (1982) 43

[3] Doak R.B. and Chizmeshya A.V.G., Europhys. Lett., 51(4) (2000) 381