A continuous-wave and pulsed electron spin resonance spectrometer operating at 275 GHz

An electron paramagnetic resonance (EPR) spectrometer is described which allows for continuous-wave and pulsed EPR experiments at 275 GHz (wavelength 1.1 mm). The related magnetic field of 9.9 T for g approximately 2 is supplied by a superconducting solenoid. The microwave bridge employs quasi-optical as well as conventional waveguide components. A cylindrical, single-mode cavity provides a high filling factor and a high sensitivity for EPR detection. Even with the available microwave power of 1 mW incident at the cavity a high microwave magnetic field B1 is obtained of about 0.1 mT which permits pi/2-pulses as short as 100 ns. The performance of the spectrometer is illustrated with the help of spectra taken with several samples.