Phosphorescence in Platinum Phthalocyanine Single Crystals Excited by Ruby Laser

Phosphorescence emission its decay time in platinum phthalocyanine (PtPc) single crystals were investigated in the near infrared region around 971 nm by Q-switched ruby laser. The intensity of phosphorescence emission around 971 nm at 4.2 K tends to saturate and its decay time begins to decrease with increasing excitation intensity above the incident photon flux of 1 ×10 23 photons/cm 2 sec. These dependence are explained in terms of triplet exciton-triplet exciton (T-T) collision. Assuming that all the excited singlet excitons are converted to the triplet exctions and the absorption coefficient of the ruby laser light is 10 5 cm -1 , the value of the bimolecular quenching rate γ is estimated to be about 1×10 -16 cm 3 /sec.