In situ microparticle diagnostics by stimulated Raman scattering

A novel technique for the identification of the chemical composition of mic rodroplets has been developed. External seeding of stimulated Stokes Raman scattering (SSRS) has been applied to reduce the minimum detectable concent ration of the minority species in multicomponent microdroplets. To avoid co mplications with polarizer and analyzer in remote sensing applications, we utilize the fact that the probed (seeded) SSRS band of the minority species (at v(min)) can efficiently pump SSRS of the majority species (at v(maj)). The Raman signal of the minority species appears at a shift of v(min+maj), which can easily be distinguished from the elastically scattered light of the seed laser at the shift of v(min). Furthermore, we investigated fluores cing microdroplets with stimulated anti-stokes Raman scattering (SARS).