Changes in the Photophysical Properties with Heavy Atoms and the Effects of Modulus for 4-Phenylphenol in Solid-Matrix Luminescence

Fluorescence and phosphorescence quantum yields and fluorescence and phosphorescence lifetimes were obtained for 4-phenylphenol adsorbed on filter paper with either NaCl, NaBr, or Nal at 296 and 93 K. From these data several photophysical parameters were calculated and compared. In general, the photophysical data showed that the heavy-atom effect was operative, with NaI showing the greatest effect. However, NaBr at 93 K showed both the heavy-atom effect and another effect which was particular to NaBr. For 4-phenylphenol with NaI, very little increase occurred for the phosphorescence quantum yield from 296 to 93 K, which indicated that almost maximum phosphorescence quantum yield was achieved at room temperature for 4-phenylphenol with NaI present. The increase in phosphorescence lifetime for 4-phenylphenol from room temperature to low temperature was shown to be related to the increase in the Young's modulus of filter paper as the temperature was lowered. Calculated phosphorescence lifetimes at room temperature and at low temperature with equations that included Young's modulus values agreed very well with experimental lifetime values.