Anomalous alignment dependence of the third-order harmonic of H2+ions in intense laser fields

Abstract

We studied the high-harmonic generation of H 2 + ions in an intense laser field by solving the time-dependent Schrödinger equation in prolate spheroidal coordinates. By analyzing the power spectra of the harmonics with the electric field polarized along the molecular axis, we found that the yield of the third-order harmonic drops by several orders of magnitude at a specified aligned angle between the laser polarization direction and the molecular axis. The laser polarization angle of the minimum depends on the internuclear distance and it disappears both in the separated-and united-atom limits. This infers that the minimum is associated with the molecular symmetry. By decomposing individual contributions of the σ and π states, we identified that the minimum is attributed to the cancellation of the induced dipole moments of the σ and π states, like a dynamical Cooper minimum, but the position of the minimum can be tuned by the laser intensity for a given internuclear distance.

Coherent control of the dissociation probability ofH2+in ω-3ω two-color fields

“…The potential energy curves and transition dipole strengths are calculated in prolate spheroidal coordinates as detailed in Ref. [21]. The peak intensity of FW is set as 2×10 14 W/cm 2 and the intensity of the THG pulse as 2×10 13 W/cm 2 .…”

Field-free molecular orientation by two-color shaped laser pulse together with time-delayed THz laser pulse

“…Molecular orientation and alignment have attracted the attention of many researchers because of their extensive applications in chemical reaction dynamics [1][2][3][4], highharmonic generation [5][6][7][8], strong-field ionization [9] and photoelectron angular distribution [10,11]. The molecular alignment has been realized by using femtosecond laser pulses [12][13][14][15][16], and can be used to control the THz emission from a two-color filament in air [17].…”