RAMAN-STUDY OF THE EFFECT OF INTENSE LASER IRRADIATION ON GRAPHITIZEDMESOPHASE SPHERULES

We have found that the Raman spectra of graphitized mesophase spherule s, heat treated at 2800 degrees C, show interesting change under inten se laser irradiation. When they are irradiated with an intense laser b eam, the width of the E(2g) band at 1580 cm(-1) decreases while the in tensity of the D band at 1350 cm(-1) increases, i.e. the correlation b etween these quantities is negative. This is an interesting finding be cause a positive correlation between these quantities has been reporte d in the case of ''thermal treatment'' in the graphitization process o f this material. We have also observed luminescence from graphitized m esophase spherules under intense laser irradiation. The intensity of t he luminescence is correlated with the change of the Raman spectra. In order to interpret these phenomena, we suggest a model in which the b ridge bonds between aromatic molecules in the graphitized mesophase sp herules are broken by intense laser irradiation. Copyright (C) 1996 El sevier Science Ltd