Use of field modulation with boxcar integrator to measure relaxation time in electron spin resonance experiments

Abstract

Field modulation is used with pulsed electron spin resonance apparatus to measure the relaxation time T₁ of weak but easily saturable paramagnetic resonances. Both a boxcar integrator and lock-in detector are used to recover the field modulation signal from the noise. The method works best for T₁ between about 1 μs and 1/10 of the field modulation period (e.g. approximately 1 ms for 100 cycles) but it may be used to measure longer relaxation times also.