Homogeneous optical dephasing and line broadening processes in an organic glass: comparison of the temperature dependences of picosecond photon echo and hole burning experiments

The homogeneous optical dephasing times (T2) and the non-photochemical hole burning (NPHB) linewidths of resorufin in glycerol glass are reported from 1.1 to 25.5 K. At low temperature, the linewidths obtained from NPHB are substantially wider than the linewidths (1/πT2) obtained from photon echo measurements, but the two become equal at high temperatures. The extra broadening of the NPHB is found to increase as T0.8. A model of homogeneous dephasing including both two-level system and pseudolocal mode contributions is successful over the entire temperature range.