Carbon dioxide laser absorption spectra of toxic industrial compounds

Abstract

CO(2) laser absorption cross-section data are reported for acrolein, styrene, ethyl acrylate, trichloroethylene, vinyl bromide, and vinylidene chloride. These data indicate that sub parts per billion level, interference-free detection limits should be possible for these compounds by the CO(2) laser photoacoustic technique. Photoacoustic detectabilities below 40 ppb should be possible for these compounds in the presence of ambient air concentrations of water vapor and other anticipated interferences. These compounds are also found not to be important interferences in the detection of toxic hydrazine-based rocket fuels by CO(2) laser spectroscopic techniques.

Trace-level detection of gases and vapours with mid-infra-red hollow waveguides

“…There is only a limited amount of CO 2 laser absorption data in the literature for C 2 HCl 3 and these suggest that the line absorption coefficients for 10P12 and 10P20 are respectively 4.1 and 12.6 atm −1 cm −1 at 1 atm pressure [18]. Similar values of 4.6 and 14.6 atm −1 cm −1 were given in [19]. Although the data presented herein suggest slightly higher values, they are comparable.…”

“…C 2 HCl 3 was selected as an appropriate VOC for investigation. Some CO 2 laser absorption coefficient data are available in the literature [18,19]. On the basis of these data and some preliminary measurements, the CO 2 laser lines 10P20 (944.2 cm −1 ) and 10P12 (951.2 cm −1 ) were considered suitable for measurement as analytical and reference wavelengths respectively.…”

A Survey of Laser and Selected Optical Systems for Remote Measurement of Pollutant Gas Concentrations

“…A key to overcoming this difficulty lies in developing the heterodyne detection technique for use with pulsed systems, since this technique should have a signal to noise ratio 3-4 orders of magnitude greater than for direct detection. 42 One requirement is to make the laser emit a pulse with a single "carrier" frequency whose width is narrow (<1 MHz), which can be accomplished by using a hybrid TEA laser, 43 by in- See also Loper et al 77 jection-locking a TEA laser, 44 or by Q-switching a CW-CO2 laser. 45 This is necessary for the heterodyne detection technique because a narrow bandwidth heterodyne receiver produces less noise.…”

Facility monitoring of toxic industrial compounds in air using an automated, fieldable, miniature mass spectrometer

“…at concentrations of 40 ppb or less in the presence of various interferents that could be found in workplace air samples. 1 However, this optical method is not easily made portable. Efforts are being made to design a portable chemical sensor array device capable of detecting toxic compounds in less than 2 min, 2 but the device requires monitoring the change in color of many dyes (24 to 36) at once and a new cartridge after every use.…”