Analysis of NO2 absorption cross-sections at high temperature for the developement of post-combustion gases optical sensor

Nitrogen dioxide is a well-known pollutant which has effect on human health, with pulmonary problems, and on the atmosphere chemistry, where it is responsible for acid rains for example. Consequently, current European standards impose very low NO₂ emission thresholds in exhaust gases. Thus, there is a need for novel sensors able to monitor small NO₂ concentrations for real time adjustments of engines performances. In this perspective, absorption spectroscopy is a method of great interest as it has been largely used in the past to measure NO₂ concentration in air atmosphere. Such measurements require the knowledge of the NO₂ absorption cross-sections. As the atmosphere is a “cold” environment, these data is only known up to 25°C. The first purpose of this study is then, to measure the absorption cross-sections of NO₂ at higher temperatures, i.e. up to 150°C. Then, based on these results, absorption measurements were performed on hot gas mixtures containing very small concentrations of NO₂ (<;5ppm). A resolution close to one part per million was observed.