Spin dynamics in HeH2+ molecular ion in intense laser fields

Abstract

A theoretical study is carried out on the effect of non-dipole interactions on the electron spin dynamics in the asymmetric diatomic HeH²⁺ in its first excited state in intense linearly polarized laser fields. The Foldy–Wouthuysen transformation is used to solve the Dirac equation numerically without BOA. Effects of the phase of the laser pulse and alignment of the molecule on the relativistic characteristics, such as the pure spin and the pure spin–orbit current densities, spin–orbit force and spin torque, are investigated. The results of this study demonstrate that population oscillates between the two spin states during the course of interaction and its configuration depends on the molecular axis orientation and initial phase of the laser pulse. Also, a small polarization takes place in the spin states, even in the absence of the spin–orbit coupling. Furthermore, spin and spin–orbit current densities are phase-dependent and affected differently by the phase of the laser pulse.