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A: Atomphysik

A 12: Posters Thursday (Ion/Atom/Molecule/Surface Scattering)

A 12.9: Poster

Thursday, April 5, 2001, 12:30–15:00, AT3

Fraunhofer diffraction of matter waves — •M. van der Poel¹, C.V. Nielsen¹, M.-A. Gearba¹, S.E. Nielsen², and N. Andersen¹ — ¹Niels Bohr Institute, Ørsted Laboratory, DK-2100 Copenhagen Ø, Denmark — ²Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark

We have constructed an apparatus combining the experimental techniques of cold target recoil-ion momentum spectroscopy (COLTRIMS) and a laser-cooled target. We measure angle differential cross sections in Li⁺ + Na(3s,3p) → Li(2s,2p) + Na⁺ electron transfer collisions in the keV regime with a recoil momentum resolution of 0.12 a.u. This yields an order of magnitude better angular resolution than previous measurements. The Li(2s) de Broglie wavelength is about 150 fm and the effective Na(3s) diameter 20 a.u. This results in a clearly resolved Fraunhofer type diffraction scattering pattern. Also, our coupled-channel calculations using a 35-state two center AO basis set compare very well with the experimental results. We consider the present results a crucial step towards COLTRIMS studies of anisotropic Na(3p) excited states.