Pressure-Induced Exciton Instability In Organic Solids Probed By Fluorescence

Abstract

Luminescence and absorption spectra under hydrostatic pressures in the range 0 -50 kbar have been studied.The instability of free excitons occurs in tetracene, anthracene and phenanthrene crystals, while the instability of self-trapped excitons occurs in a-perylene and pyrene crystals.Experimental results lead to a conclusion that the exciton -phonon coupling constants in those materials are well expressed as a function of the intermolecular distance between nearest -neighbor, plane -parallel molecules.