Anomalous temperature-dependent phosphorescence of Cu porphin in anthracenea)

The temperature dependence of the phosphorescence spectrum of copper porphin in anthracene has been studied from room temperature down to 8 K and the 4.2 K spectrum has been obtained. A 23.4 cm−1 crystal field splitting of the orbital components of the TQ state was observed. The 0–0 transition appears abruptly at approximately 25 K and increases rapidly in intensity as the temperature is lowered. A model involving energy transfer from the copper porphin to the triplet exciton band of anthracene gives a satisfactory explanation for the anomalous temperature dependence of the copper porphin phosphorescence intensity.