Frequency-modulation-enhanced magnetic rotation spectroscopy has been shown to be a sensitive and selective technique for detecting local concentrations of gaseous NO<sub>2</sub>. Detection levels of 20 parts in 10<sup>9</sup> have been achieved in the laboratory (in the presence of larger ambient atmospheric levels). Simple signal-processing algorithms, demonstrated here, promise detection levels at the parts-in-10<sup>12</sup> level. Improvements are suggested for further optimization of the technique, and the effects of background atmospheric NO<sub>2</sub> levels are discussed.
© 1995 Optical Society of America
J. M. Smith, J. C. Bloch, R. W. Field, and J. I. Steinfeld, "Trace detection of NO2 by frequency-modulation-enhanced magnetic rotation spectroscopy," J. Opt. Soc. Am. B 12, 964-969 (1995)