Shake-off in XFEL heated solid density plasma

TL;DR

This paper reports the first observation of shake-off electron ejection in solid-density plasma heated by an XFEL, demonstrating its persistence at high temperatures and emphasizing its importance in plasma spectral modeling.

Contribution

First experimental detection of shake-off in XFEL-heated solid-density plasma, confirming theoretical predictions and highlighting its role in plasma emission spectra interpretation.

Findings

Shake-off persists up to 10 eV temperatures at solid density

Observed shake-off matches predicted probabilities for solids

Implication for plasma modeling and spectral analysis

Abstract

In atoms undergoing ionisation, an abrupt re-arrangement of free and bound electrons can lead to the ejection of another bound electron (shake-off). The spectroscopic signatures of shake-off have been predicted and observed in atoms and solids. Here, we present the first observation of this process in a solid-density plasma heated by an x-ray free electron laser. The results show that shake-off of L-shell electrons persists up to temperatures of 10 eV at solid density, and follow the probability predicted for solids. This work shows that shake-off should be included in plasma models for the correct interpretation of emission spectra.