On line monitoring of composite nanoparticles synthesised in pre-industrial laser pyrolysis reactor using laser-induced breakdown spectroscopy (LIBS)

Abstract : Laser Induced Breakdown Spectroscopy (LIBS) was employed for on-line and real time process monitoring during nanoparticle production by laser pyrolysis. Laser pyrolysis has proved to be a reliable and versatile method for nanoparticle production. However, an on-line and real time monitoring system could greatly enhance the process optimization and accordingly improve its performances. For this purpose, experiments aiming at demonstrating the feasibility of an on-line monitoring system for silicon carbide nanoparticle production using the LIBS technique were carried out. Nanosecond laser pulses were focused into a cell through which part of the nanoparticle flux diverted from the production process was flowed for LIBS analysis purposes. The nanoparticles were vaporized within the laser-induced plasma created in argon used as background gas in the process. Temporally resolved emission spectroscopy measurements were performed in order to control nanoparticle stoichiometry. Plasma parameters such as temperature and electronic density were calculated using Boltzmann plot and Stark broadening analysis respectively. Local thermodynamic equilibrium was justified and thus stoichiometry was deduced in great agreement with the nanoparticles production. These promising results put forward the possibility of the nanoparticle stoichiometry monitoring during the production process.