# Plasma screening in mid-charged ions observed by K-shell line emission

## TL;DR

The paper measures how plasma environments affect ion electronic structures using x-ray free electron lasers and K-shell line emissions.

## Contribution

A novel experimental method to quantify plasma screening effects via energy shifts in K-shell line emissions.

## Key findings

- Plasma screening effects were experimentally quantified using XFEL-driven energy shifts in K-shell transitions.
- Detailed electronic configurations were identified from Kα, Kβ, and Kγ line emissions.
- The findings can improve models of plasma screening and related effects like ionization potential depression.

## Abstract

Dense plasma environment affects the electronic structure of ions via variations of the microscopic electrical fields, also known as plasma screening. This effect can be either estimated by simplified analytical models, or by computationally expensive and to date unverified numerical calculations. We have experimentally quantified plasma screening from the energy shifts of the bound-bound transitions in matter driven by the x-ray free electron laser (XFEL). This was enabled by identification of detailed electronic configurations of the observed K\documentclass[12pt]{minimal}
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\begin{document}$$\upalpha$$\end{document}α, K\documentclass[12pt]{minimal}
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\begin{document}$$\upgamma$$\end{document}γ lines. This work paves the way for improving plasma screening models including connected effects like ionization potential depression and continuum lowering, which will advance the understanding of atomic physics in the Warm Dense Matter regime.