PRELIMINARY RESULTS ON THE EFFECT OF LASER HEATING ON CARBON NANOPARTICLES SAMPLED FROM A PREMIXED FLAME

Carbon nanoparticles produced as by-product of combustion processes are actually considered an interesting resource to be employed in different applications, spanning from gas sensing to electronics. This interest is due to the peculiar properties of the nanoparticles sampled from flames at first stages of their formation. By changing the experimental conditions of the flame or simply the sampling height of the particles from flame, it is possible to tailor nanoparticles with specific property. In this context, following our previous studies on the effect of laser irradiation on carbon nanoparticles, laser heating of nanoparticles is suggested as an interesting tool to change and control their optical properties. In this work we investigate the effect of laser heating on carbon nanoparticles produced in a premixed flame. Particles are sampled from flame and irradiated on-line by using the fundamental beam of a pulsed Nd:YAG laser. On-line wavelength-resolved extinction measurements are carried out in the visible range on pristine and laser heated nanoparticles. To this purpose a laser heating unit is employed consisting in a tube where the nanoparticles are sent in line with the extinction measuring section. The aerosol sampling flow rate and laser frequency are adjusted in order to heat the particles by a single shot. Particles are then collected on filters for Raman spectroscopy. By coupling our results information on optical properties, and in particular optical band gap, and particle nanostructures are obtained and discussed.