Ammonia trace measurements at ppb level based on near-IR photoacoustic spectroscopy

被引:0
作者
J.-P. Besson
S. Schilt
E. Rochat
L. Thévenaz
机构
[1] Ecole Polytechnique Fédérale de Lausanne (EPFL),Nanophotonics and Metrology Laboratory
[2] Omnisens SA,undefined
来源
Applied Physics B | 2006年 / 85卷
关键词
Modulation Depth; Saturation Regime; Laser Modulation Frequency; Photoacoustic Sensor; Ammonia Trace;
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学科分类号
摘要
A photoacoustic sensor using a laser diode emitting near 1532 nm in combination with an erbium-doped fibre amplifier has been developed for ammonia trace gas analysis at atmospheric pressure. NH3 concentration measurements down to 6 ppb and a noise-equivalent detection limit below 3 ppb in dry air are demonstrated. Two wavelength-modulation schemes with 1f and 2f detection using a lock-in amplifier were investigated and compared to maximise the signal-to-noise ratio. A quantitative analysis of CO2 and H2O interference with NH3 is presented. Typical concentrations present in ambient air of 400 ppm CO2 and 1.15% H2O (50% relative humidity at 20 °C) result in a NH3 equivalent concentration of 36 ppb and 100 ppb, respectively.
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页码:323 / 328
页数:5
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