Transient EPR

Transient EPR (trEPR) spectroscopy is a continuous-wave EPR method by which photoexcited paramagnetic species, such as molecular multiplet states and radical pairs, may be examined in a time-resolved manner following pulsed laser excitation. The method provides kinetic information on a nanosecond timescale and longer, unperturbed by any spectrometer dead time. Spectral information is obtained by detecting the transient magnetization at a fixed time after the laser pulse and varying the magnetic-field strength over the region in which resonances are expected. trEPR has proven to be indispensable for studies of paramagnetic intermediates in photoactive proteins, such as photosynthetic reaction centers and blue light photoreceptors under ambient conditions, and materials for organic photovoltaic devices.