Time resolved studies of pentacene triplets by electron spin echo spectroscopy

Abstract

The triplet kinetics of pentacene imbedded in p-terphenyl and benzoic acid crystals have been studied by electron spin echo spectroscopy in the temperature range of 77–300 K. Population inversions have been observed for both H0‖‖x and H0‖‖z in the benzoic acid crystal but only for H0‖‖z in the p-terphenyl crystal at room temperature. Detailed analyses showed that the triplet population and decay of the pentacene are very much host and temperature dependent. Dimer formation and tautomerization (proton transfer of the benzoic acid dimer) may be responsible for the peculiar triplet kinetics of the pentacene in the benzoic acid crystal.