Polarization dependence of absorption and luminescence spectra of a 1,5-dihydroxyanthraquinone single crystal

A study has been made on the polarization dependence of absorption and luminescence spectra of a 1,5-dihydroxyanthraquinone single crystal with the thickness of 0.5 mm, which was prepared by gas phase growth method. The luminescence and absorption spectra were measured by various excitation energy at various temperatures. The thin film crystal of micrometer thickness was also prepared by unique crystal growth method. It was grown in a very thin space gap between a couple of quartz plates and annealed very gradually. The absorption spectra were measured by a direct transmission method at room temperature. Consideration of the electronic configuration was carried out by molecular orbital calculation. The absorption band around 3eV and the luminescence around 2eV are assigned to the transition between HOMO and LUMO states.