NONINVASIVE SPECTROSCOPIC DETECTION OF BULK-POLYMERIZATION BY STIMULATED RAMAN-SCATTERING

The polymerization of styrene in a 15-cm storage bottle and of methyl methacrylate (MMA) inside a 50-cm reactor cell was monitored noninvasi vely by stimulated Raman scattering (SRS) for spectroscopic analysis. A pulsed laser was required to stimulate Raman scattering while a phot odiode array detector measured the monochromator-dispersed Stokes line s. The results demonstrate that SRS is a useful spectroscopic techniqu e for the real-time probing of polymerization in a large sample volume . Its signal intensity is related to the average analyte concentration integrated over the laser interaction path, which can better represen t the bulk property of extended sample dimensions.