Photo-ionization of polarized lithium atoms out of an all-optical atom trap: A complete experiment

TL;DR

This study demonstrates a complete photo-ionization experiment of polarized lithium atoms using an all-optical trap and COLTRIMS spectrometer, achieving high resolution to analyze electron emission and partial wave contributions.

Contribution

It presents a novel all-optical setup for preparing polarized excited lithium atoms and performing detailed photo-ionization measurements with high resolution.

Findings

High-resolution momentum analysis of emitted electrons and ions.

Agreement of measured photo-electron angular distributions with theoretical models.

Characterization of target and spectrometer properties for precise measurements.

Abstract

An all-optical, near-resonant laser atom trap is used to prepare an electronically excited and polarized gas target at mK-temperature for complete photo-ionization studies. As a proof-of-principal experiment, lithium atoms in the 2$^2$P$_{3/2}$($m_l$=+1) state are ionized by a 266 nm laser source, and emitted electrons and Li$^+$ ions are momentum analyzed in a COLTRIMS spectrometer. The excellent resolution achieved in the present experiment allows not only to extract the relative phase and amplitude of all partial waves contributing to the final state, it also enables to characterize the experiment regarding target and spectrometer properties. Photo-electron angular distributions are measured for five different laser polarizations and described in a one-electron approximation with excellent agreement.