Triplet Exciton Dynamics in Hexachlorobenzene Single Crystals

Publisher Website
Google Scholar
Abstract
The singlet-singlet excitation spectrum of triplet exciton phosphorescence for pure single crystals of hexachlorobenzene is reported and compared with the direct absorption spectrum. The observed antibatic behaviour is explained by a mechanism of diffusive random walk of the triplet exciton with surface quenching. No singlet exciton dominated rate processes were detected. The measured diffusion coefficient Dc*c* perpendicular to the ab plane was 2.4 × 10−5cm2sec−l. The diffusion coefficient for charge carriers was measured to be 10−2 cm2 sec−1. The mobilities of these charge carriers were μ+ = 1.2 cm2 V−l sec−l and μ− = 0.96 cm2 V−1 sec−l. The temperature dependence of Dc*c* was studied. There was no evidence for long-range trap-to-trap migration of the exciton. Above 115 °K no temperature dependence of the mean free path was observed. From the measured spectral band width of the polarized absorption spectrum the mean exciton scattering time was calculated as 2.4 × 10−14 sec. The combined coulombic and exchange interaction energy of the triplet excited molecule and its nearest neighbour alongthe c* direction was 1 cm−1.

This publication has 28 references indexed in Scilit: