The triplet state of C 60 studied by zero-field absorption-detected magnetic resonance

Abstract

Using absorption-detected magnetic resonance (ADMR) in zero field on C 60 in a frozen toluene/polystyrene glass at temperatures between 6 and 40 K we observed two distinct triplet states. Their zero-field splitting parameters were determined by ADMR double resonance to be | D I|=(114.6±1)×10 −4 cm −1, | E I|=(4.8±1)×10 −4 cm −1, | D II|=(99±10)×10)×10 −4 cm −1, and | E II|=(17±10)×10 −4 cm −1. Triplet I was identified as the molecular triplet state of C 60 found earlier in frozen glasses, whereas triplet II was ascribed to either residual C 60 clusters or a subpopulation of the molecules in an environment allowing for partial averaging of the dipolar splitting due to a fast pseudo-rotation mechanism.