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Photo-induced Polymerization and the Relaxation in Liquid Sulfur
In order to study dynamical properties of the polymerization transition in liquid sulfur we have measured the transient absorption spectra after illuminating pulsed laser below and above the polymerization temperature, T_p. For the measurement we have developed a specially designed optical cell made of quartz. The thickness of liquid specimen contained in the cell was less than 1μm, which enabled us to measure the change of optical absorption spectra accompanying the polymerization. We have found that the photo-induced polymerization occurs below T_p. When the relaxation to the thermal equilibrium state occurs after stopping the illumination there appear two different relaxation processes, that is, the fast and slow ones. The fast one is observed just after stopping the illumination of pulsed laser and the relaxation time is about 30 seconds. The slow one follows the fast one and the relaxation time is of the order of one or ten minutes. On the basis of these findings we propose a possible idea that the fast relaxation process corresponds to the relaxation from a polymeric chain to a charge-transfer complex and the slow one the relaxation from the charge-transfer complex to the most stable ring molecules.
広島大学総合科学部紀要. IV, 理系編