SEDL / STP / STP721-EB / STP27567S

Laser Techniques for Analysis of Ambient Air

Gelbwachs, JA
Manager, Applied Laser Spectroscopy Section, and head, Analytical Sciences Department, the Aerospace Corp., El Segundo, Calif.

Jones, PF
Manager, Applied Laser Spectroscopy Section, and head, Analytical Sciences Department, the Aerospace Corp., El Segundo, Calif.

Pages: 17    Published: Jan 1980

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Abstract

Laser techniques based on Raman scattering, absorption, and fluorescence have been used successfully in analyzing ambient air samples, as well as in probing plumes remotely. The sensitivity limits have ranged from 1 ppm to 0.02 ppb for air samples and down to 50 ppb for probing at a distance of 1 km in the lower portion of the atmosphere. When the appropriate lasers are available, long-path infrared (IR) absorption with wavelength modulation is the most sensitive technique, but fluorescence detection is often simpler. Of the newer techniques under investigation, multiphoton photoionization should have the potential for the lowest detection limits—one molecule in the laser beam or 10³ to 10⁴ molecules/cm³.