ELASTIC ELECTRON HELIUM SCATTERING SPECTRA ASSISTED

BY A CO2 LASER FIELD

M. Ghalim*, F. Mastour, S. Barmaki

Laboratoire de Physique Atomique et Moléculaire

Université HASSAN II. Faculté des Sciences Aïn Chock

B. P. 5366, Maârif. Km 8, route d’El Jadida, Casablanca, Maroc.

* Corresponding author. E-mail : ghalim@wanadoo.net.ma

Received 24 November 2000

Abstract

We have studied theoretically the electron spectra in the elastic scattering of a fast electrons (Ei = 9.5 eV) by helium atoms in the presence of a CO2 monochromatic laser field and in the presence of a CO2 bichromatic laser field. The former is linearly polarized, and has moderate intensity (I=108 Wcm-2) with photon energy . The latter has the same polarization and has two components of frequencies w and 2w which are out of phase by an arbitrary angle j. Our numerical results (in the Born approximation) show that the scattered signal is sensitive to the collision geometry. Otherwise it is easily controllable by the phase variations, especially at the quadrature of the phase (j = p/2) the signal in the presence of the CO2 monochromatic laser can be reproduced by a CO2 bichromatic laser field with less intensity what would be a great advantage in laser spectroscopy.

Keywords: Electron; He-atom; Scattering geometry; Monochromatic laser; Bichromatic laser; Phase control.

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