Absolute measurement of laser ionization yield in atmospheric pressure range gases over 14 decades

TL;DR

This paper reports absolute measurements of laser ionization yields in atmospheric pressure gases over 14 decades, revealing effects of gas contaminants and confirming theoretical rates for atoms and molecules.

Contribution

It introduces a novel measurement method for high-density gases and provides the first extensive data on ionization yields at atmospheric pressure.

Findings

Ionization yields span 14 decades in atmospheric gases.

Results align with theoretical ionization rates for isolated species.

Gas contaminants significantly influence laser-gas interactions.

Abstract

Strong-field ionization is central to intense laser-matter interactions. However, standard ionization measurements have been limited to extremely low density gas samples, ignoring potential high density effects. Here, we measure strong-field ionization in atmospheric pressure range air, N2 and Ar over 14 decades of absolute yield, using mid-IR picosecond avalanche multiplication of single electrons. Our results are consistent with theoretical rates for isolated atoms and molecules and quantify the ubiquitous presence of ultra-low concentration gas contaminants that can significantly affect laser-gas interactions.