LOCALIZED EXCITON STATES OF DOPED NAPHTHALENE CRYSTALS

Bands due to localized exciton states in a crystal arising near guest molecules have been obtained and studied in the absorption and luminescence spectra of a naphthalene crystal (T = 4.2 °K) doped with heterocyclic compounds (thionaphthene, i = T, indole, i = I, and benzofurane, i = B). The luminescence spectrum of these states is similar to the exciton luminescence spectrum of naphthalene: the polarization ratio Pi(b/a) for 0‐0 bands in the luminescence and absorption spectra decreases with 0‐0 bands approaching to the a‐component of the Davydov doublet. Simultaneously depolarization of the A1‐band occurs. From comparison between the polarization ratios for 0‐0 bands of the localized and impurity states (the case of isotopic mixtures) their common features as well as differences are found the latter being apparently due to the localized centre structure. The results are qualitatively explained on the basis of the theory of localized exciton states. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim