Low-order harmonic generation of hydrogen molecular ion in laser field studied by the two-state model

Abstract

The low-order harmonic generation of hydrogen molecular ion interacting with a linearly polarized laser field has been investigated theoretically by using a simple two-state model. The validity of the two-state model is carefully examined by comparing the harmonic spectra of hydrogen molecular ion obtained from this model with those from the three-dimensional time-dependent Schrödinger equation. When combined with the Morlet transform of quantum time-frequency spectrum, the two-state model can be used to study the dynamical origin of the low-order harmonic generation of hydrogen molecular ion driven by low-frequency pulses. In addition, some interesting structures of the time profiles for low order harmonics are obtained.

Role of the dressed and bound states on below-threshold harmonic generation of He atom*

“…For the molecules, Avanaki et al [16] found that the 3rd, 5th, and 7th harmonics of H + 2 molecular ion were split in double peaks due to the resonance between the ground 1σ g and the first excited 1σ u states, and we [17] explain the reason due to the interference of the different cycles between the lowest two bound states of H + 2 ion by using a twostate model. [18] Therefore, the bound states have an important role on the BTHG of atom and molecule.…”