A PULSED EPR AND ENDOR SPECTROMETER OPERATING AT 95 GHZ

The construction and performance of a pulsed EPR/ENDOR spectrometer operating at a frequency of 95 GHz is described. The spectrometer is equipped with a tunable, cylindrical TE(011) cavity and allows for measurements at liquid-helium temperatures, for orientational studies of single crystals with an angular accuracy of 0.3 degrees, for optical excitation and detection of the emitted light, and for radiofrequency excitation to perform ENDOR experiments. It is shown that a 10-fold improvement in absolute sensitivity and a 6-fold improvement in time resolution is obtained when using a single-mode TE(011) cavity instead of a multimode Fabry-Perot resonator. The advantages of pulsed EPR and ENDOR spectroscopy at 95 GHz are illustrated with the results of three recent investigations. (C) 1995 Academic Press, Inc.