Inhomogeneous Broadening and Excited-Vibrational-State Lifetimes in Low-Temperature Organic Mixed Crystals

Abstract
We have determined the extent of residual inhomogeneous broadening in the "sharp" mixed-crystal spectrum of the large organic molecule pentacene; and we report a technique for the direct fluorescence measurement of excited-vibrational-state bandwidths. We have found the lifetime of the 267-cm1 vibronic band in pentacene to be greater than 0.2 nsec.