Anisotropic saturation of the electron spin resonance in the photo-excited triplet state of pyrene-d-10

Abstract
Electron spin saturation measurements have been performed on the optically excited triplet state of pyrene-d-10 in biphenyl. An order of magnitude anisotropy is found in the amount of power needed to saturate the spin resonance as the molecule is rotated in the external magnetic field. Relaxation times have been inferred at room temperature and the anisotropy is found to be consistent with that predicted by the modulation of the electron spin-spin interaction. For pyrene-d-10 in biphenyl: