Online elemental characterization of collimated nanoaerosols by laser-induced breakdown spectroscopy of isolated particles

Abstract

We present a new setup for the online elemental characterization of nanoaerosols during their gas-phase synthesis using Laser-Induced Breakdown Spectroscopy (LIBS). This system involves the interaction of a kHz rate pulsed laser with a collimated jet of particles under vacuum conditions (10⁻² mbar). The low-pressure interaction reduces spectral line broadening, enhances spectral resolution, and eliminates the background continuum from the laser-gas interaction, improving LIBS detection capabilities. A sampling stage has also been incorporated into the design, enabling the continuous analysis of nanoaerosols during their high-throughput synthesis. This feature enhances the instrument's versatility and opens new possibilities for studying nanoparticle formation and properties in situ and in real-time.

The proof of concept was produced by an experiment of online elemental analysis of Li₂TiO₃ nanoparticles during their synthesis by laser pyrolysis. The monitoring of the LIBS emission signal of the particles in real time was demonstrated by measuring the signals from the three elements together with data conditional analysis to extract the events information. Moreover, the specific detection of Li signals was achieved in a single-nanoparticle detection mode, enabling it to reach an absolute detection limit of 150 ag. The collimation step of particles in a jet, combined with a high repetition rate laser, opens the way to specific monitoring of low-density aerosols in the sub-micrometer range.