Field and frequency modulated sub-THz electron spin resonance spectrometer

Christian Caspers,M Ali Haider,Murari Soundararajan,Jean-Philippe Ansermet,Pedro Freire Da Silva

doi:10.1063/1.4945450

Abstract

260-GHz radiation is used for a quasi-optical electron spin resonance (ESR) spectrometer which features both field and frequency modulation. Free space propagation is used to implement Martin-Puplett interferometry with quasi-optical isolation, mirror beam focusing, and electronic polarization control. Computer-aided design and polarization pathway simulation lead to the design of a compact interferometer, featuring lateral dimensions less than a foot and high mechanical stability, with all components rated for power levels of several Watts suitable for gyrotron radiation. Benchmark results were obtained with ESR standards (BDPA, DPPH) using field modulation. Original high-field ESR of 4f electrons in Sm3+-doped Ceria was detected using frequency modulation. Distinct combinations of field and modulation frequency reach a signal-to-noise ratio of 35 dB in spectra of BDPA, corresponding to a detection limit of about 1014 spins.

Highlights

Field and frequency modulated sub-THz electron spin resonance spectrometer
260-GHz radiation is used for a quasi-optical electron spin resonance (ESR) spectrometer which features both field and frequency modulation
We demonstrate with 1,3-bisdiphenylene-2-phenylallyl (BDPA), a radical that has a narrow ESR line, that the proper combination of an optically focusing sample holder with field modulation at high frequencies provides a distinct optimum in signal-to-noise ratio (SNR)

Summary

Introduction

Field and frequency modulated sub-THz electron spin resonance spectrometer 260-GHz radiation is used for a quasi-optical electron spin resonance (ESR) spectrometer which features both field and frequency modulation.

Results

Conclusion