Generation of below-threshold even harmonics by a stretched H2+ molecular ion in intense linearly and circularly polarized laser fields
Journal
Physical Review A - Atomic, Molecular, and Optical Physics
Journal Volume
92
Journal Issue
6
Date Issued
2015
Author(s)
Abstract
We explore the mechanism of below-threshold even-harmonic generation of the H2+ molecular ion subject to intense near-infrared linearly and circularly polarized laser fields. The task is accomplished by accurate treatment of the time-dependent Schrödinger equation in prolate spheroidal coordinates within the generalized pseudospectral formalism. Even harmonics are detected in the harmonic spectra of stretched molecules, mostly with the internuclear separations of 5 to 9 a.u. Consecutive dynamic localization of the electron density near each of the nuclei is responsible for the broken inversion symmetry, which in turn leads to emission of low-order even harmonics. An intuitive picture of the process is provided by the analysis of the time evolution of the electron density and time-frequency spectra of the dipole acceleration. A clear theoretical explanation of the phenomenon is given within the Floquet formalism.
Type
journal article