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Main Title Investigation of Resonant Optoacoustic Cells.
Author Plyler, Robert R. ; Patty, Richard R. ;
CORP Author North Carolina State Univ. at Raleigh.;Environmental Sciences Research Lab., Research Triangle Park, NC.
Year Published 1983
Report Number EPA-R-805332; EPA-600/3-83-070;
Stock Number PB83-251637
Additional Subjects Air pollution ; Gas detectors ; Trace elements ; Resonance radiation ; Laser beams ; Comparison ; Concentration(Comparison) ; Gas analysis ; Chemical analysis ; Sampling ; Design criteria ; Performance evaluation ; Foreign technology ; Acoustooptics ; Air pollution detection ; Elliptical cells ; Helmholtz cells ; Resonant cells
Library Call Number Additional Info Location Last
NTIS  PB83-251637 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 33p
A theory describing the optoacoustic signal is presented; dependence on both cell and gas parameters are given and the advantage of operating at a resonant frequency is discussed. Three elliptical cells with major axes 5.8, 12.7, and 15.2 cm (corresponding minor axes 5.5, 11.0; and 7.6 cm) were utilized as resonant optoacoustic cells. Longitudinal standing waves analagous to radial resonances for a cylindrical cell were driven by passing the beam from a CO2 laser along one focus of the ellipse. Results are compared with measurements on a Helmholtz cell for which the minimum detectable absorption coefficient was about 2 x 10 to the -7th power cm. Windowless operation was attempted, and the results indicate that further improvement is possible.