ABSTRACT
Novel implementations of single-fiber laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy systems that gated light switches based on frustrated total internal reflection are described. The switching devices are largely wavelength independent, with full temporal and spatial separation of laser and fluorescence light. Wavelength-independent beam separation or beam combination schemes can be implemented for coaxial optical setups, e.g., in single-fiber or telescopic experimental arrangements. Selected practical examples of schemes for qualitative and quantitative analytical spectroscopy are discussed.
ABSTRACT
The application of laser-induced breakdown spectroscopy to the analysis of single biological microparticles (bioaerosols) is described, exemplified here for a range of pollens. Spectra were recorded by exposure of the pollen to a single laser pulse from a Nd:YAG laser (lambda = 1064 nm, Ep approximately 30 mJ). The intensities of the single-pulse laser-induced breakdown spectra fluctuated dramatically, but an internal signal calibration procedure was applied that referenced elemental line intensities to the carbon matrix of the sample (represented by molecular bands of CN and C2). This procedure allowed us to determine relative element concentration distributions for the different types of pollen. These pollens exhibited some distinct concentration variations, for both major and minor (trace) elements in the biomatrix, through which ultimately individual pollens might be identified and classified. The same pollen samples were also analyzed by Raman microscopy, which provided molecular compositional data (even with spatial resolution). These data allowed us to distinguish between biological and nonbiological specimens and to obtain additional classification information for the various pollen families, complementing the laser-induced breakdown spectroscopy measurement data.
