One-photon excitation in thee-H collision in the presence of a laser field

Abstract

We consider the one-photon excitation of atomic hydrogen by electron impact in the presence of a homogeneous monochromatic linearly polarized electric field as a model for the radiation field of the laser. In the framework of the approximative approach of Faisal and Rahman [in Fifth International Conference on Atomic Physics, edited by R. Marrus, M. H. Prior, and H. A. Stutgart (University of California, Berkeley, 1976), p. 49], suited for high-energy electrons, we present an analytic expression for the transition amplitude to an arbitrary nlm state, in terms of hypergeometric Gauss and Appell I'I functions, together with the numerical results for excitation to the n =4 states. PACS number(s): 32.90.+a, 34.80.Qb

Inelastic scattering of electrons by metastable hydrogen atoms in a laser field

“…(35) and (36) have a similar form compared to the definitions of P and Q reported in Ref. [15] for laser-assisted inelastic e − -H(1s) scattering, but obviously the expressions of electronic I nl and atomic J nll ′ radial integrals are different, since in the present work the hydrogen atom is initially in its metastable 2s state. Next, after the derivation of a general formula for the one-photon differential scattering cross section we present some particular cases where Eq.…”

“…We found out a qualitative agreement with the inelastic earlier results calculated in a two-level approximation at resonance photon energy [30] showing the accuracy and efficiency of our results. The dynamics of the laserassisted inelastic e − -H(2s) collisions accompanied by one-photon absorption differs both qualitatively and quantitatively from that involving the ground state [15] due to the high polarizabilities of the excited states. The presented numerical data for each subshell of the n = 4 level indicates that at small scattering angles the atomic dressing effects for inelastic collisions are significantly stronger than for elastic e − -H(2s) scattering.…”

“…In addition, we must only keep the leading terms in the calculation of the electronic and atomic transition amplitudes Eqs. (15) and (17). Substituting the partial wave expansion of the exponential term, exp (iq · r), in the form factor Eq.…”

“…(iii) The dressing of the hydrogen atom by the laser field, i.e., the modification of the target atom in the laser field, is described within the first-order time-dependent perturbation theory (TDPT) in the field [33]. Working in the approximation approach described in [15] and [31] we derive an analytic formula for DCS in the laser-assisted inelastic scattering of fast electrons by H(2s) accompanied by one-photon exchange. Section III is devoted to discussion of the numerical results where the angular distributions and the resonance structure of the DCS's are analyzed for the excitation of the n = 4 subshells.…”

“…for forward and backward scattering. We should note that in Eqs (15). the field and the projectile electron contributions to transition amplitude T(0) nlm are completely decoupled, since the laser field dependence of the electronic transition amplitude is contained in the argument of the Bessel function, α 0 · q, only.…”