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Updated: Jun 21, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Precision measurements of NH(3) spectral lines near 11 microm using the infrared heterodyne technique
Abstract:
Absolute line-center frequencies for eleven lines of ammonia in near coincidence with CO(2)-laser transitions have been determined to accuracies of +/-3 MHz by infrared heterodyne detection. These results were obtained by heterodyning a blackbody with a stable, grating-tuned CO(2) gas laser. A discussion of the apparatus and method of calculation, including error analysis, is presented. With these accurately determined line-center positions, the ammonia molecule will be a useful secondary-frequency standard for diode-laser spectroscopy in the 11-microm wavelength region.
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