Ultrasensitive gas detection by quartz-enhanced photoacoustic spectroscopy in the fundamental molecular absorption bands region

A trace gas sensor based on quartz-enhanced photoacoustic spectroscopy with a quantum cascade laser operating at 4.55 m as an excitation source was developed. The sensor performance was evaluated for the detection of N₂O and CO. A noise-equivalent (1) sensitivity of 4 ppbv N₂O with 3 s response time to (1-1/e) of the steady-state level was demonstrated. The influence of the relevant energy transfer processes on the detection limits was analyzed. Approaches to improve the current sensor performance are also discussed. PACS 42.62.Fi; 43.35.Sx