When DNA is hit with ultraviolet light, it can lose excess energy from radiation by ejecting the core of a hydrogen atom — a single proton — to keep other chemical bonds in the system from breaking. To gain insight into this process, researchers used X-ray laser pulses from the Linac Coherent Light Source (LCLS) at the Department of Energy’s SLAC National Accelerator Laboratory to investigate how energy from light transforms a relatively simple molecule, 2-thiopyridone.