On the selective multiphoton ionization of sodium by femtosecond laser pulses: Apartial-wave analysis

Multiphoton ionization of sodium by femtosecond laser pulses of 800nm wavelength in the range of laser peak intensities belonging to the over-the-barrier ionization domain is studied. Photoelectron momentum distributions and the energy spectra are determined numerically by solving the time dependent Schrodinger equation for three values of the laser intensity from this domain. The positions of peaks related to Freeman resonances in the calculated spectra agree with the peak positions in the spectra obtained experimentally by Hart et al. [7]. A partial wave analysis of these peaks revealed that each peak is a superposition of the contributions of photoelectrons produced by the resonantly enhanced multiphoton ionization via different intermediate states. It is demonstrated that at appropriate laser intensities the selective ionization, which occurs predominantly through a single intermediate state, is possible. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the multiphoton ionization of sodium by femtosecond laser pulses at 800nm wavelength, within the over-the-barrier ionization domain. Results show that selective ionization through a single intermediate state is possible under appropriate laser intensities.