Single Particle LIBS

Laser-induced breakdown spectroscopy (LIBS) is ideally suited to function as a real-time, in situ monitor characterized by speed and experimental simplicity, and is sensitive enough for measuring aerosol elemental composition as well as overall mass concentrations. Ensemble averaging has historically been used to overcome the extensive laser shot-to-shot spectral fluctuations, thereby improving sensitivity of the LIBS technique. Ensemble averaging, however, reaches a natural limit when low to very low aerosol concentrations comprise the analyte species of interest. For the unique problem of aerosol analysis, the point-sampling nature of the LIBS technique plays an important role in LIBS data processing, and conditional spectral analysis may be used as defined by the presence or absence of discrete particles in a corresponding plasma volume. Conditional data analysis algorithms applied to individual spectra can improve signal-to noise ratios as well as enable the study of single-shot LIBS spectra corresponding to individual aerosol particles. Single-shot LIBS analyses of aerosols raises new questions regarding shot-to-shot fluctuations and data precision, as well as issues involving the fundamental interaction between the laser-induced plasma and aerosol particles. These issues are explored in the context of quantitative LIBS-based analysis of single aerosol particles.