In situ, real-time detection of soot particles coated with NaCl using 193 nm light

摘要

We report in situ, real-time detection of soot particles coated with NaCl using excimer laser fragmentation fluorescence spectroscopy (ELFFS). Carbon atom fluorescence at 248 nm and the Na D-line at 589 nm are used as signatures of soot and NaCl, respectively. Soot particles are encapsulated with a NaCl layer in a well-controlled inverted flame burner. NaCl particles are injected into the methane-air co-flow flame to coat the soot particles. ArF laser irradiation of the coated particles in an air stream at 1.14 J/cm~2 produces fluorescence from Na, C, and CH. At 0.69 J/cm~2, which is slightly above the fluorescence threshold, but not enough for considerable fragmentation of the particles, Na D-line persists with little carbon and no CH observed. These results suggest that the photolytic fragmentation-fluorescence using 193 nm excitation can be effectively used for in situ, real-time chemical analysis of core-shell nanoparticles.