Singlet-Triplet Interactions in Crystalline Anthracene

Abstract

A new carrier-generation mechanism is observed in anthracene and is attributed to singlet-triplet annihilation. The rate constant for ionization following this annihilation is estimated to be ${\ensuremath{\alpha}}_{\mathrm{ST}}\ensuremath{\simeq}{10}^{\ensuremath{-}12}$ ${\mathrm{cm}}^{3}$ ${\mathrm{sec}}^{\ensuremath{-}1}$. The experiments give also a new value for the singlet-singlet annihilation rate constant, ${\ensuremath{\alpha}}_{\mathrm{SS}}\ensuremath{\simeq}{2.10}^{\ensuremath{-}11}$ ${\mathrm{cm}}^{3}$ ${\mathrm{sec}}^{\ensuremath{-}1}$. The possibility of other interpretations of the data is discussed.