Effect of Electron Spin Polarization on Laser-Assisted Semirelativistic Excitation of Atomic Hydrogen from the Metastable 2s State to the 4s State in a Circularly Polarized Laser Field

Abstract

This paper presents a semirelativistic theoretical study of a laser-assisted inelastic electron-atom scattering. Specifically, we investigate the laser-assisted excitation of atomic hydrogen from the metastable 2s state to the 4s state, induced by electron impact with particular emphasis upon spin-dependent effects. The analysis is carried out within the framework of the first Born approximation, while the interaction of the incident and scattered electrons with the laser field is described using Dirac–Volkov states. An analytical expression for the spin-unpolarized differential cross section is derived, providing a reference for assessing the consistency and reliability of the adopted theoretical approach. In addition, the spin-flip and spin–non-flip differential cross sections are investigated. The numerical results show that the spin-flip contribution is negligible compared with the spin–non-flip contribution over the range of parameters considered, indicating that spin-conserving transitions dominate the excitation process.