When it comes to producing high-quality electron beams like those found in state-of-the-art scientific equipment like free-electron lasers, ultrafast electron diffraction and imaging and wakefield accelerators, scientists have looked to photocathode technology as a way to convert light to electrons. These tools give researchers a way to more deeply penetrate into materials and atomic structure and behavior under real-world conditions.
source https://phys.org/news/2021-03-tiny-diamonds-excellent-material-components.html