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Measurement of trace gas concentration with pressure-calibration method based on wavelength modulation absorption spectrometry

A theoretical description of pressure-calibration method based on wavelength modulation absorption spectrometry (WMAS) with second harmonic detection for precise measurements of trace gas concentration will be present in this paper. The method can obtain the consistent relation between gas concentration and second harmonic signal in pressure changes. The signal is monotonic function when gas concentration as metrics and it becomes a complete linear function when density of particles number as metrics. It not only allows complying with traditional WMAS technique without any calibration methods, but also applying to various environment of pressure variations. Typical applications like environmental monitoring and remote sensing can be used this method to calibrated measurement results. In addition, the method is not restricted to situations with typical applications. Furthermore, it can also easily be adapted to various gas concentration detection under pressure changes. The pressure-calibration method can be useful for gas concentration measurements so that assist to ensure the accuracy of data in research.