Multiple ionization of neon by soft X-rays at ultrahigh intensity

TL;DR

This study investigates neon atom ionization at ultrahigh intensity using free-electron laser pulses, comparing experimental yields with theoretical models to understand ionization dynamics up to charge state 6+.

Contribution

It provides a quantitative comparison of experimental ionization yields with minimal and elaborate models, highlighting the models' limitations at higher charge states.

Findings

Minimal model accurately predicts ionization up to 5+ charge state.

Experimental yields exceed predictions for charge states above 5+.

Ionization dynamics are complex at higher charge states, requiring more sophisticated modeling.

Abstract

At the free-electron laser FLASH, multiple ionization of neon atoms was quantitatively investigated at 93.0 eV and 90.5 eV photon energy. For ion charge states up to 6+, we compare the respective absolute photoionization yields with results from a minimal model and an elaborate description. Both approaches are based on rate equations and take into acccout a Gaussian spatial intensity distribution of the laser beam. From the comparison we conclude, that photoionization up to a charge of 5+ can be described by the minimal model. For higher charges, the experimental ionization yields systematically exceed the elaborate rate based prediction.