Transient Extreme Ultraviolet Spectroscopy: A Probe of Ultrafast Charge Dynamics in Solid-State Materials

Abstract

Over the past two decades, Transient Extreme Ultraviolet Spectroscopy (Tr-XUV) has evolved into a unique probe of ultrafast electronic dynamics. In this review, we summarize several advances and applications of this technique to study solid-state materials. We first discuss how this technique enables understanding of small polaron formation in varying chemical environments. We then describe its ability to unravel charge transfer across interfaces, followed by an analysis of its distinctive access to charge localization through giant resonances. Finally, we discuss instances where its combination with other ultrafast spectroscopies facilitates a more complete physical picture. Together, these advances demonstrate that ultrafast core-level spectroscopy in the ultraviolet regime reveals a comprehensive framework for nonequilibrium dynamics that establishes it as a versatile frontier technique for materials science.