QEPAS methane sensor performance for humidified gases

A trace gas sensor based on quartz enhanced photoacoustic spectroscopy (QEPAS) was evaluated using humidified nitrogen samples and ambient air. Relaxation processes following vibrational excitation of 2 nu(3) state of CH4 were investigated. Sensor performance at different gas pressures could be predicted based on a developed kinetic model. The experimentally determined normalized detection sensitivity for CH4 in humid gas is 1.0x10(8) cm(-1) W/Hz(1/2).