Maximum information photoelectron metrology

TL;DR

This paper demonstrates the use of tomographic reconstruction to obtain full 3D photoelectron momentum distributions from multiphoton ionization, revealing new interference effects and symmetry-breaking phenomena in photoelectron angular distributions.

Contribution

It introduces a method to record and analyze complete 3D photoelectron data, uncovering additional physical insights beyond traditional 2D measurements.

Findings

Good agreement with previous 2D data

Revealed unexpected symmetry-breaking

Identified additional ionization pathways

Abstract

Photoelectron interferograms, manifested in photoelectron angular distributions (PADs), are a high-information, coherent observable. In order to obtain the maximum information from angle-resolved photoionization experiments it is desirable to record the full, 3D, photoelectron momentum distribution. Here we apply tomographic reconstruction techniques to obtain such 3D distributions from multiphoton ionization of potassium atoms, and fully analyse the energy and angular content of the 3D data. The PADs obtained as a function of energy indicate good agreement with previous 2D data and detailed analysis [Hockett et. al., Phys. Rev. Lett. 112, 223001 (2014)] over the main spectral features, but also indicate unexpected symmetry-breaking in certain regions of momentum space, thus revealing additional continuum interferences which cannot otherwise be observed. These observations reflect the presence of additional ionization pathways and, most generally, illustrate the power of maximum information measurements of this coherent observable.