Comment on "Mott scattering in strong laser fields"

The first Born differential cross section for Mott scattering of a Dirac-Volkov electron is reviewed. The expression (26) derived by Szymanowski [Phys. Rev. A 56, 3846 (1997)] is corrected. In particular, we disagree with the expression of (dsigma/dOmega) they obtained and we give the exact coefficients multiplying the various Bessel functions appearing in the scattering differential cross section. Comparison of our numerical calculations with those of Szymanowski shows qualitative and quantitative differences when the incoming total electron energy and the electric-field strength are increased particularly in the direction of the laser propagation.