Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 1: Posters Monday (Cluster, Atoms in Fields)

A 1.34: Poster

Montag, 2. April 2001, 12:30–15:00, AT3

Atomic Photodetachment Microscopy — •Christophe Blondel and Christian Delsart — Laboratoire Aimé-Cotton, Centre national de la recherche scientifique, bâtiment 505, F-91405 Orsay cedex, France

Photodetachment microscopy consists of recording the freed electron interferogram produced when a negative ion undergoes photodetachment in the presence of an electric field. Sensitivity of the interference pattern to the ejection energy of the electron makes the apparatus the most sensitive ever used for electron spectrometry. Accuracies in the µeV range can be reached, which is three orders of magnitude better than in classical electron spectrometry.

Though the method only applies to very slow electrons, with less than 100 µeV of kinetic energy, it can be used to determine with the best accuracy the electron affinity of any element, if one can excite the corresponding anion with a single mode laser just above its detachment threshold. A review of the electron affinities so measured will be presented.

In addition, more recent calculations have shown how robust the phase of the interferograms is, with respect to the rather fast motion of the anions in the actual experiment. A comparison of the photodetachment microscope with other dual-wave interferometers, either in the electron or light optics domain, will also be presented.