Berlin 2001 – scientific programme

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A: Atomphysik

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

A 5.24: Poster

Tuesday, April 3, 2001, 12:30–15:00, AT3

Excess Photon Detachment of H⁻ in a Strong Infrared Laser Field — •Igor Yu. Kiyan, Rainer Reichle, and Hanspeter Helm — Fakultät für Physik, Freiburg University, Stefan-Meier-Str.19, 79104 Freiburg

Angular resolved momentum spectra of photoelectrons formed in photodetachment of H⁻ ions are recorded using an electron imaging technique. The negative ions are exposed to a laser pulse of 130 fs duration, generated from an OPA at the wavelength of 2150 nm. Saturation of the photodetachment process at the leading front of the laser pulse restricts laser intensities that negative ions experience before their depletion. At least three excess photon detachment (EPD) peaks are observed in the energy spectrum of the photoelectrons. The ponderomotive broadening of the energy spectrum is of the order of 150 meV. This corresponds to the maximum intensity experienced by the negative ion of ∼ 3× 10¹¹ W/cm². The analysis of the angular distribution of the photoelectrons shows high angular momentum contributions which arise from from EPD channels with reemission of photons.

Supported by DFG (SFB 276, TP C14)