Time-resolved laser-induced breakdown spectrometry of aerosols
The repetitive breakdown spark from a focused laser beam was used to generate analytically useful emission spectra of aerosols in air. The apparatus is simple; a pulsed laser and optics, a spectrometer, and some method for time resolution of the spark light. Time resolution is essential because of the strong continuum emission at early times (<500 ns). High temperatures in the spark result in vaporization of small particles, dissociation of molecules, and excitation of atomic and ionic spectra. The plasma acts as if it were in local thermodynamic equilibrium, at least after 1 ..mu..s. Spectroscopic methods have been used to measure the time-resolved temperatures and electron densities. A simple one-dimensional hydrodynamic model predicts the temperature and diameter of the spark. Beryllium in atmospheric pressure air has been detected at 0.7 ..mu..g/m/sup 3/, which is 0.6 ng/g of air (RSD = 30%). Limits of detection have also been established for Na, P, As, and Hg in air. A calibration curve linear over 4 orders of magnitude has been developed for Na in air. In situ experiments have been performed on two experimental coal gasification systems, and real-time spectral information has been obtained in both cases. 37 references, 9 figures, 2 tables.
- Research Organization:
- Los Alamos National Lab., NM
- OSTI ID:
- 5000978
- Journal Information:
- Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 55:8; ISSN ANCHA
- Country of Publication:
- United States
- Language:
- English
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CHEMICAL ANALYSIS
COAL GASIFICATION
ECOLOGICAL CONCENTRATION
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FLUIDS
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