Coherent Raman beat and ESEEM EPR spectroscopy applied to a transition metal complex: comparisons of sensitivity and spectral resolution

Coherent Raman beats (CRB) resulting from 14N hyperfine interactions have been observed in the EPR spectrum of the S = 12 state of a mixed valence di-μ-oxo bridged Mn(III, IV) bipyridyl dimer at X-band (9 GHz) and the results compared with those obtained from three-pulse electron spin echo envelope modulation (ESEEM) data recorded under similar conditions. The spectral resolution of the CRB data were ≈-fold superior-to the ESEEM while the signal-to-noise ratio was enhanced by a factor of ≈40. The resolution improvement derives from the fact that the CRBs can persist for times approaching the electron T1 while the decay of the ESE envelope is limited by spectral diffusion. CRB detection benefits from a multiplex advantage relative to ESEEM.