Single molecule polarization spectroscopy: Pentacene in p-terphenyl

Polarized light spectroscopy has been performed on single pentacene molecules in p-terphenyl single crystals. Thin crystal flakes of p-terphenyl doped with a very low concentration of pentacene have been grown by sublimation. The orientation of the transition dipole moment of the pentacene molecules in the d/b'-plane of the crystal was determined by taking the birefringence of the crystalline matrix into account. An assignment of the pentacene sites O-1, O-2, O-3 and O-4 to the crystallographic position M(1), M(2), M(3) and M(4) of the p-terphenyl triclinic unit cell is proposed.