Measurement of the longitudinal relaxation time by continuous-wave, nonlinear electron spin resonance spectroscopies

We characterize a continuous-wave, nonlinear electron spin resonance spectroscopy which detects the longitudinal component of the magnetization. It is demonstrated that the signal is proportional to the Laplace transform of a relaxation function with decay time equal to the longitudinal relaxation time T1. The conclusion is reached by comparing T1 to the effective time T(eff)1 being drawn by progressive saturation for a nitroxide radical dissolved in supercooled o-terphenyl. Copyright 1998 Academic Press.