Laser-assisted electron-atom scattering

Abstract. Collision theory is briefly reviewed in the framework of the wave operator theory of quantum dynamics which emphasizes the role played by the resonances. Exact expressions of the on-shell S and T matrices are derived for an exactly solvable model which describes several resonances decaying into several channels. This model is especially relevant for investigating the physics near energy thresholds. The formalism is applied to giant resonances and to a model of laser-assisted electron-atom scattering. 

Abstract. We address the question of the importance of relativity in selected non-linear radiative processes to be observed when an atomic system is submitted to an intense radiation field. To this end, we report on recent results obtained in the theoretical analysis of the following processes i) two-photon transitions in high-Z hydrogenic systems, ii) laser-assisted Mott scattering of fast electrons, and iii) two-colour photoionisation spectra of atoms in the simultaneous presence of two ultra-intense laser fields. In each case, the signature of relativistic effects is evidenced. 

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