A multi-frequency high-field pulsed EPR / ENDOR spectrometer

TL;DR

This paper presents a versatile multi-frequency pulsed EPR/ENDOR spectrometer operating at 110-336 GHz, enabling advanced electron spin and nuclear resonance experiments with high field capabilities.

Contribution

It introduces a novel multi-frequency high-field pulsed EPR/ENDOR spectrometer with a broad frequency range and demonstrates its application in spin polarization and ENDOR measurements.

Findings

Successful operation across 110-336 GHz frequencies.

Effective detection of Mn2+ impurities at 12 T.

Demonstration of pulsed ENDOR with 39K nuclei.

Abstract

We describe a pulsed multi-frequency electron paramagnetic resonance spectrometer operating at several frequencies in the range of 110-336 GHz. The microwave source at all frequencies consists of a multiplier chain starting from a solid state synthesizer in the 12-15 GHz range. A fast PIN-switch at the base frequency creates the pulses. At all frequencies a Fabry-Perot resonator is employed and the pi/2 pulse length ranges from ~100 ns at 110 GHz to ~600 ns at 334 GHz. Measurements of a single crystal containing dilute Mn2+ impurities at 12 T illustrate the effects of large electron spin polarizations. The capabilities also allow for pulsed electron nuclear double resonance experiments as demonstrated by Mims ENDOR of 39K nuclei in Cr:K3NbO8.