Pulsed EPR spectrometer with injection-locked UCSB free-electron laser

We describe the first free-electron laser (FEL)-based pulsed electron paramagnetic resonance (EPR) system designed to study spin dynamics and structure changes of proteins in aqueous solution with nano-second of time resolution. This novel approach opens up the possibility for high-power sub-THz and THz pulsed EPR spectroscopy.