TIME-RESOLVED SPECTROSCOPIC STUDY OF THE INITIAL PROCESS OF PHOTOPOLYMERIZATION IN A DIACETYLENE CRYSTAL

The optical absorption change and luminescence induced by electron-pul se irradiation have been studied for crystalline 5,7-dodecadiyne-1,12- diol bis[phenylcarbamate] (TCDU). The triplet state of TCDU is identif ied for the first time; it shows an optical absorption band at 3.96 eV and a luminescence band at 2.57 eV. At higher temperature, the reacti ve dimer which shows an absorption band at 2.53 eV is generated. Exami nation of the correlation between the decay of the lowest triplet stat e and the dimer formation strongly suggests that the dimer is formed n ot via the lowest triplet state, but through relaxation at higher exci ted states.