Ionization of hydrogen atom driven by ultrashort intense laser pulses: study in momentum space of phase-dependent effects

• Published in: Indian journal of physics Vol. 98; no. 6; pp. 1937 - 1950
• Main Authors: Tetchou Nganso, H. M., Abdouraman, Kwato Njock, M. G.
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 01.05.2024; Springer Nature B.V
• Subjects: Angular momentum; Astrophysics and Astroparticles; Coulomb potential; Energy spectra; Hydrogen atoms; Infrared lasers; Ionization; Lasers; Momentum; Original Paper; Photoelectrons; Physics; Physics and Astronomy; Schrodinger equation; Time dependence; Wave functions; Wave packets; Above-threshold ionization; Time-dependent Schrödinger equation; Nonlocal Coulomb potential; Momentum space; Sturmian basis sets; Carrier-envelope phase
• ISSN: 0973-1458; 0974-9845
• DOI: 10.1007/s12648-023-02972-w

To bypass the difficulty of solving the one-electron time-dependent Schrödinger equation in momentum space with the interacting nonlocal Coulomb potential, we have recently formulated an alternative accurate and efficient ab initio treatment (Ongonwou et al., Ann Phys 375:471, 2016; Ekogo et al., Phys Scr 97:115402, 2022), which relies on the expansion of the atomic wave function and the interacting nonlocal Coulomb potential on a discrete basis set of Coulomb Sturmian functions in momentum space. To further illustrate the validation and credibility of our proposed theoretical and numerical approaches, we study the above-threshold ionization of the hydrogen atom exposed to ultrashort infrared, ultraviolet, and low-and-high-frequency laser pulses. The energy spectra, momentum, angular distributions of the photoelectrons, and bound-state populations at the end of the laser pulse have been numerically evaluated, analyzed, and compared against predictions of other well-known time-dependent calculations in the literature. They are obtained either by using the ionized wave function or by projecting the total electron wave packets at the end of the laser pulse onto the continuum states constructed using the incoming Coulomb wave function. We explore the physical observables’ dependence on the carrier-envelope phase of the laser pulses. Our theoretical model captures the left–right dependence and breaks backward–forward symmetry in the emitted photoelectron momentum and angular distributions.