Measurement of ammonia by a portable UV-DOAS gas sensor based on multi-pass cell

Abstract

Ammonia, the third most important abundant nitrogen compound, is a primary alkaline gas in the atmosphere. It has strong absorption bands in the deep ultraviolet (DUV) spectral range and so can be reliably detected by the differential optical absorption spectroscopy (DOAS) technique. A portable UV-DOAS gas sensor based on multi-pass cell has been designed to detected trace gases, especially for ammonia, in the DUV spectral range, with good performance using a broad-band Deuterium source and high-sensitivity spectrometer. With the optical path as long as 20m, such a sensor could detected NH3 concentrations as low as 100ppb according to the result of in-situ measurement. Fast response time and low measurement error of this portable gas sensor could be competent for emergency monitoring.