An antimonide diode laser operating near 2.65 μm was used to measure absorption lines of NO gas in the first overtone band. A blended line pair of NO that is sufficiently free of interference from H<sub>2</sub> O to permit the selective detection of NO under reduced pressure conditions was identified. With wavelength-modulation spectroscopy, a rms noise level equivalent to an absorbance of 3.2 × 10<sup>−5</sup> was achieved at a measurement integration time (for a single spectral data point) of 0.1 s. The corresponding detection sensitivity (signal-to-noise ratio of 2) for NO in air at reduced pressure was ~15 ppm m (ppm is parts in 10<sup>6</sup>). Antimonide diode lasers show substantial promise for gas-sensing applications because they can gain access to relatively strong absorption lines of several gases of environmental interest at operating wavelengths at which cryogenic cooling is not required.
© 1997 Optical Society of America
Daniel B. Oh and Alan C. Stanton, "Measurement of nitric oxide with an antimonide diode laser," Appl. Opt. 36, 3294-3297 (1997)