Nature Physics, Published online: 08 August 2024; doi:10.1038/s41567-024-02594-x
A bright, ultrashort X-ray pulse is used to transiently create and characterize warm dense copper. As the pulse intensity is increased, the opacity of copper is strongly altered. The recorded X-ray absorption spectra, substantiated by a theoretical electronic structure model, provide insight into the non-equilibrium electron dynamics during the formation of warm dense matter.
