Magnetic Dichroism in Few-Photon Ionization of Polarized Atoms

TL;DR

This paper investigates how polarized lithium atoms respond to femtosecond laser pulses, revealing angular asymmetries in emitted electrons that depend on laser parameters, with results matching quantum simulations.

Contribution

It demonstrates that electron emission asymmetries in few-photon ionization of polarized atoms can be used to probe quantum interference effects.

Findings

Angular asymmetries depend on laser intensity and wavelength.

Experimental spectra agree with quantum simulations.

Interference between partial waves explains angular shifts.

Abstract

We consider few-photon ionization of atomic lithium by linearly polarized femtosecond laser pulses, and demonstrate that asymmetries of the electron angular distribution can occur for initially polarized (2p, m=+1) target atoms. The dependence of the photoelectron emission angle relative to the electric field direction is investigated at different laser intensities and wavelengths. The experimental spectra show excellent agreement with numerical solutions of the time-dependent Schroedinger equation. In the perturbative picture, the angular shift is traced back to interferences between partial waves with mean magnetic quantum number <m>$\ne$0. This observation allows us to obtain quantum mechanical information on the electronic final state.