In Situ Approaches for Diagnostics of Nanoparticles in Plasmas*

Plasmas are widely used for synthesis of various nanomaterials. Plasma-mediated methods offer industrial scale of production while being less expensive and environmentally friendly compared to chemical and mechanical methods. They also hold a promise for controllable synthesis, due to the ability to control the plasma characteristics and plasma-induced chemistry. So far, the understanding of the interplay between the plasma and the synthesized products was dependent on the ex-situ analysis and recently a demand emerges for in-situ diagnostic techniques for characterizing the nanomaterials in the gas phase. We present three different techniques for measurement of nanoparticles. Coherent Raleigh Brillouin Scattering (CRBS) relies on scattering of photons from particles trapped in a laser interference pattern. Laser-induced incandescence (LII) technique interprets the cooling pattern from the particles heated by a laser, to obtain their sizes. Laser-induced breakdown spectroscopy (LIBS) detects nanostructures and diagnoses their chemical composition. We also show examples of their application in carbon arc.