Abstract

The physical background of a laser Stark spectrometer dedicated to the measurement of ammonia slip through DeNo_x reactors in power stations is treated. The dependence of the ammonia measurement on temperature and pressure variations is derived and verified experimentally. Selection of spectral lines with both a good absorption coefficient and a high sensitivity to the Stark effect, within the range of the CO₂ laser, has been carried out. If a ¹²CO₂ laser is used at a temperature of 573 K and at atmospheric pressure, the 10R8 laser line is recommended for best results. The 10R18 line of the ¹³CO₂ laser yields a still higher sensitivity (detection limit 0.4 ppm) for a moderate electric field. Theoretical predictions for the sensitivity of ammonia detection are compared with experimental data. Results of measurements in an industrial environment are presented.

© 1993 Optical Society of America

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