Two-photon double ionization of helium by chirped few-cycle attosecond pulses: From nonsequential to sequential regime

Abstract

The two-photon double ionization (TPDI) dynamics of helium by chirped attosecond pulses are theoretically studied by solving the two-electron time-dependent Schrödinger equation in its full dimensions. We show that both the differential and the total double ionization probability can be significantly controlled by adjusting the chirp. The dependence of the TPDI on the chirp can be quite different for different photon energies, relying on the central photon energy being in the sequential region, nonsequential region, or translation region. The physics which lead to the chirp dependence for different photon energies are addressed. Present findings are well reproduced by a model based on the second-order time-dependent perturbation theory.

Chirp-dependent ionization of hydrogen atoms in the presence of super-intense laser pulses*

“…There are many different types of chirped pulses used in the experimental and theoretical studies, and those chirped laser pulse can be categorized into linear [28][29][30][31][32][33][34] and nonlinear chirped pulse. [35,36] Especially, two different expressions of the linear chirped pulse with Gaussian shape have been given by Tong et al [29] and Barmaki et al, [30] which have been used by experimental and theoretical physicists respectively. So, we intend to explore the effects of chirped pulse with different forms on the dynamic interference for the ionization of hydrogen atoms in the ground state.…”

“…1, we present some properties for the chirped laser pulses of two forms which have been used in some literature. [29,30] The peak amplitude A 0 (ξ ), instantaneous carrier frequency ω(t) and timedependent envelope F(t) are written as follows. The laser of first form can be expressed as [29] (refer as form 1 in figures throughout this paper)…”

Interference effect of photoionization of hydrogen atoms by ultra-short and ultra-fast high-frequency chirped pulses*

“…[23][24][25] Recently, there has been widespread interest in the studies of interaction between atoms/molecules and strong chirped laser pulses. [26][27][28][29][30][31] It is interested to see the effect of a chirp attosecond pulse on the dynamic interference of the ground state hydrogen atoms. Does adding chirp will enhance or weaken the dynamic interference?…”

Tunneling exits of ${{\rm{H}}}_{2}^{+}$ in strong laser fields

“…Ionization of atoms and molecules in strong laser fields is overwhelmingly important. [1,2] Ionization carries the information of the target structures, which may be used to image atoms or molecules. The photoelectron probability and momentum spectrum allow us to understand the ultrafast dynamics during the ionization.…”