Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 5: Posters Tuesday (Photoionisation, Multi Photon Processes)

A 5.32: Poster

Dienstag, 3. April 2001, 12:30–15:00, AT3

Adiabatic evolution of atomic populations in gaussian light pulses — •Mohand Brouri, Vola M. Andrianarijaona, Jozo Jureta, and Xavier Urbain — Département de Physique, Université Catholique de Louvain, Belgium

In a two-colour experiment, we plan to study the time evolution of the excited population of a three-level atomic system. A continuous wave Ar-ion laser operating on the 488nm line (singlemode) illuminates a fast beam of metastable atoms and is Doppler detuned in order to match the frequency of the 2s-4p transition in atomic hydrogen. The interaction region extends on about one centimetre, and is probed by a sharply focused infrared beam that selectively ionises the 4p population, giving an instantaneous picture of the system.

With this experimental scheme, we aim at demonstrating the deviation from the Rabi formula in the adiabatic excitation regime associated with gaussian pulses. The available power should be sufficient to observe, exactly on resonance, three to four complete Rabi cycles. The adiabatic evolution out of resonance will cause the populations to evolve in a monotonous and reversible manner throughout the interaction zone.