Semirelativistic 1s−2s1s-2s excitation of atomic hydrogen by electron impact

In the framework of the first Born approximation, we present a semirelativistic theoretical study of the inelastic excitation ($1s_{1/2}\longrightarrow 2s_{1/2}$) of hydrogen atom by electronic impact. The incident and scattered electrons are described by a free Dirac spinor and the hydrogen atom target is described by the Darwin wave function. Relativistic and spin effects are examined in the relativistic regime. A detailed study has been devoted to the nonrelativistic regime as well as the moderate relativistic regime. Some aspects of this dependence as well as the dynamic behavior of the DCS in the relativistic regime have been addressed.Comment: one latex file and 6 figure

Comment on Mott Scattering in strong Laser Field

The first differential cross section for Mott scattering of a Dirac-Volkov electron is reviewed. The expression (26) derived by Szymanowski et al. [Physical Review A {\bf 56}, 3846,(1997)] is corrected. In particular, we disagree with the expression of $(\frac{d\sigma}{d\Omega})$ they obtained and we give the exact coefficients multiplying the various Bessel functions appearing in the scattering differential cross section.Comment: 16 pages, LaTex, added reference for section 3, corrected some typosReport no: LPHEA 02-0