Ultrafast electrons and high-powered lasers have uncovered surprisingly strong radiation signals in everyday semiconductors, according to a new study published in the journal Nature Photonics. The research, led by scientists from Stanford University and the Department of Energy's SLAC National Accelerator Laboratory, aimed to explore how different materials respond to high-energy electron exposure. This work could lead to better sensing technologies by offering new insights into how materials behave under intense energy conditions. The team used a state-of-the-art tool called the Megaelectronvolt Ultrafast Electron Diffraction (MeV-UED) instrument at SLAC's Linac Coherent Light Source (LCLS) to send high-energy electrons into samples of II-VI semiconductors. These materials, which include compounds like zinc sulfide and cadmium telluride, are commonly used in various electronic devices. Instead of relying on traditional methods that detect light emissions from scintillator materials, the researchers used synchronized laser pulses to observe the materials’ optical responses right after the electrons caused ionization. The researchers initially expected the charge created by the high-energy electrons to spread out evenly across the semiconductor samples. However, they found that the charge carriers—pairs of electrons and holes generated when atoms are struck—clustered together in dense, localized regions. This unusual behavior altered the materials' band gaps, which are the energy ranges that determine how materials absorb and emit light. This shift could change how semiconductors interact with light, potentially offering new ways to manipulate their optical properties. The findings suggest that these effects might also be achievable in systems that use lower energy, opening the door to new imaging technologies. These could be used for real-time monitoring and diagnosis of diseases by offering more precise and detailed imaging capabilities. The research was led by Diana Jeong, an instructor in radiology at Stanford University, and included contributions from scientists at the University of Central Florida and SLAC National Accelerator Laboratory.