Excitation and ionization of the hydrogen atom by intense femtosecond chirped laser pulses

Abstract

The excitation and ionization processes of the hydrogen atom by intense femtosecond chirped laser pulses are investigated by solving numerically the three-dimensional time-dependent Schrödinger equation. We study, in three distinct cases, the interaction of the atomic system with chirped pulses of different central carrier frequencies that correspond to some harmonics of a Ti–sapphire laser. We analyze, in each case, the mechanism of the population transfer from the ground to the excited electronic states and show how it differs depending on the sign of the chirp parameter. We also show that the ionization yield is sensitive to the chirp parameter when resonant or near-resonant transitions are induced by the chirped pulses. The latter are efficient to control the excitation process by inducing selective population transfer when compared with unchirped pulses.

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

“…( 4), (5), and (7) does not depend on the chirp, i.e., all the spectrum profiles of the chirped pulses remain the same as the tranform-limited case. We notice that in the recent study, [53] the definition of the chirped pulses does not make sure the spectrum profile is independent on the chirp, though in a related work about H atom [57] by the same authors exactly the same definition for the chirped pulses with the present work is taken. It is in fact our initial motivation to see how a more physical definition for the chirp pulse will influence the conclusion of Ref.…”

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.…”

Above-threshold ionization of hydrogen atom in chirped laser fields

“…Theoretically, Nakajima et al [17] investigated the ATI of Na by chirped infrared laser pulses by solving the three-dimensional time-dependent Schrödinger equation (3D-TDSE) and attributed the chirp dependence of the photoelectron angular distributions (PADs) to the excited bound states in the multiphoton ionization processes. Laulan et al [18] studied excitation and ionization of hydrogen atoms in intense chirped laser pulses. Xiang et al [19] found that the cutoff of the ATI of one-dimensional H atoms can be extended dramatically using a few-cycle nonlinear chirped laser pulse.…”