EPR and Optical Absorption Studies of γ-irradiated Pyrene Single Crystals

Abstract

Abstract Pyrene single crystals irradiated with γ rays at room temperature have been investigated by electron paramagnetic resonance and optical absorption experiments. EPR spectra exhibit a triplet characteristic and each line of the triplet shows characteristic features with rotations of the crystals in a magnetic field. From analyses of these spectra the presence of two kinds of hydrogen added pyrene radicals, 3-H2-pyrene and 2-H2-pyrene radicals, is concluded. In the optical absorption spectrum nine main absorption bands have been detected. These absorption bands are compared with the theoretically calculated transition energies with SCF-CI molecular orbital calculations for 3-H2-pyrene and 2-H2-pyrene radicals. Reasonable correspondences are obtained between theoretical values and the experimental spectrum.