Assessment of the Upper Particle Size Limit for Quantitative Analysis of Aerosols Using Laser-Induced Breakdown Spectroscopy

Abstract

The laser-induced plasma vaporization of individual silica microspheres in an aerosolized air stream was investigated. The upper size limit for complete particle vaporization corresponds to a silica particle diameter of 2.1 microm for a laser pulse energy of 320 mJ, as determined by the deviation from a linear mass response of the silicon atomic emission signal. Comparison of the measured silica particle sampling rates and those predicted based on Poisson sampling statistics and the overall laser-induced plasma volume suggests that the primary mechanism of particle vaporization is related to direct plasma-particle interactions as opposed to a laser beam-particle interaction. Finally, temporal and spatial plasma evolution is discussed in concert with factors that may influence the vaporization dynamics of individual aerosol particles, such as thermophoretic forces and vapor expulsion.

Laser assisted plasma spectrochemistry: laser ablation

“…The number of particles and their size distribution also depends on the laser irradiance, as well as wavelength, fluence, ambient gas and pressure, and properties of the sample. 24,31,35,36,55,[67][68][69][76][77][78] The particle influence on fractionation and analytical performance is a critical area that needs to be thoroughly investigated. Fig.…”

On-line monitoring of composite nanoparticles synthesized in a pre-industrial laser pyrolysis reactor using Laser-Induced Breakdown Spectroscopy

“…Carranza and Hahn demonstrated incomplete vaporization of micrometric-sized particles even for high laser irradiance and concluded the existence of an upper particle size of 2.1 µm beyond which vaporization was not completed [24]. In addition, possible depletion of nanometric-sized particles from the plasma core was also reported [25].…”

Nanoparticle Mass Spectrometry: Pushing the Limit of Single Particle Analysis

“…When particles are analyzed at atmospheric pressure and the laser initiates a plasma in the surrounding gas, particles up to several micrometers in diameter can be completely vaporized. 40 In the vacuum of a mass spectrometer where the particle itself initiates the plasma, the upper size limit may be smaller although particles over 100 nm in diameter have been analyzed. In addition to the detection of small particles, the laser-induced plasma also efficiently ionizes a wider range of chemical compositions.…”