The role of spin and angular momentum in strong-field ionization

TL;DR

This study measures electron spin polarization during strong-field multiphoton ionization of xenon, revealing how spin and angular momentum influence ionization probabilities and resulting in opposite spin polarizations for different ionic states.

Contribution

It provides the first detailed experimental analysis of spin polarization effects linked to angular momentum states in strong-field ionization of xenon.

Findings

Opposite spin polarizations observed for different ionic states.

Spin polarization magnitude is twice as high for J=1/2 compared to J=3/2.

Ionization probability depends strongly on magnetic quantum number sign.

Abstract

The spin polarization of electrons from multiphoton ionization of Xe by 395 nm circularly polarized laser pulses at $6\cdot10^{13}$ W/cm$^2$ has been measured. At this photon energy of 3.14 eV the above threshold ionization peaks connected to Xe$^+$ ions in the ground state ($J=3/2$, ionization potential $I_p=12.1$ eV) and the first exicted state ($J=1/2$, $I_p=13.4$ eV) are clearly separated in the electron energy distribution. These two combs of ATI peaks show opposite spin polarizations. The magnitude of the spin polarization is a factor of two higher for the $J=1/2$ than for the $J=3/2$ final ionic state. In turn the data show that the ionization probability is strongly dependent on the sign of the magnetic quantum number.