Development of a spectrometer using a continuous wave distributed feedback quantum cascade laser operating at room temperature for the simultaneous analysis of N2O and CH4 in the Earth's atmosphere

We report on the development and performance of a gas sensor based on a distributed feedback quantum cascade laser operating in continuous wave at room temperature for simultaneous measurement of nitrous oxide (N2O) and methane (CH4) concentrations at ground level. The concentrations of the gases are determined by a long path infrared diode laser absorption spectroscopy. The long-term stability of the instrument is evaluated using the Allan variance technique. A preliminary evaluation of the instrument performance is realized by in situ measurements of N2O and CH4 concentrations at ground level during 1 day. The sensor has also been applied to study the time response of N2O concentrations to a fertilizer addition in a soil sample and for the comparison between various types of soils. (c) 2008 Optical Society of America.