Abstract
A quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor system was developed for the sensitive detection of hydrogen peroxide (H2O2) using its absorption transitions in the v(6) fundamental band near 7.73 mu m. The recent availability of distributed-feedback quantum cascade lasers (DFB-QCLs) provides convenient access to a strong H2O2 absorption line located at 1295.55 cm(-1). Sensor calibration was performed by means of a water bubbler that generated titrated average vapor concentrations. A minimum detection limit of 75 parts per billion (ppb) was achieved at a pressure of 80 torr for a 1 sec data acquisition time. The long-term repeatability and stability of the sensor was investigated by measuring time-varying H2O2 mixtures for similar to 2 hrs. An Allan deviation analysis was performed to investigate the longterm performance of the QEPAS sensor system, indicating the feasibility of a minimum detection limit of 12 ppb using the optimum data averaging time of 100 sec.