Raman Investigation of Photopolymerization Reactions of Single Optically Levitated Microparticles

Raman spectroscopy was used to investigate polymerization reactions in a single micrometer-sized monomer droplet. An Ar + laser levitated the microparticles and simultaneously excited the Raman scattering. The polymerization reaction was initiated by exposing the monomer droplets to the UV radiation of a mercury arc excitation lamp. The Raman spectrum of the reacting particle was investigated on-line. The results demonstrate that the combination of the technique of optical levitation and Raman spectroscopy allows nondestructive in situ measurements of single particles and is therefore very useful for the study of fundamental processes.