Photoinduced polymerization and relaxation in liquid sulphur

Abstract

In order to study the dynamics of the polymerization in liquid sulphur we have measured the transient absorption spectra after illuminating with a pulsed laser below and above the polymerization temperature, Tp. We have found that photoinduced polymerization occurs below Tp and there exist two kinds of relaxation process, that is, the fast and slow ones. The slow one can be observed after illumination with a very weak pulsed laser and the relaxation time is of the order of ten minutes. The fast one is observed just after stopping the illumination of a rather stronger pulsed laser and the relaxation time is about 30 seconds. The fast one is always followed by the slow one. On the basis of these findings we conclude 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 molecule. With further increase of the intensity of the pulsed laser we have found that giant molecules with colloidal form are generated and they lie on parallel lines. The relaxation time is about one minute.