Broadband detection of methane and nitrous oxide using a distributed-feedback quantum cascade laser array and quartz-enhanced photoacoustic sensing

摘要

Here we report on the broadband detection of nitrous oxide (N2O) and methane (CH4) mixtures in dry nitrogen by using a quartz-enhanced photoacoustic (QEPAS) sensor exploiting an array of 32 distributed-feedback quantum cascade lasers, within a spectral emission range of 1190?1340?cm?1as the excitation source. Methane detection down to a minimum detection limit of 200?ppb at 10?s lock-in integration time was achieved. The sensor demonstrated a linear response in the range of 200?1000?ppm. Three different mixtures of N2O and CH4in nitrogen at atmospheric pressure have been analyzed. The capability of the developed QEPAS sensor to selectively determine the N2O and CH4concentrations was demonstrated, in spite of significant overlap in their respective absorption spectra in the investigated spectral range.