| Abstract: | A novel spectroscopic technique based on modulation spectroscopy with two excitation sources and quartz enhanced photoacoustic spectroscopy is described. We demonstrated two potential applications of this detection technique. First, we investigated the measurement of small temperature differences in a gas mixture. In this case, a sensitivity of 30 mK in 17 sec was achieved for a C2H2/N2 gas mixture with a 0.5% C2H2 concentration. Second, we demonstrated the detection of broadband absorbing chemical species, for which we selected hydrazine as the target molecule and achieved a detection limit of ∼1 part per million in 1 sec. In both cases, the measurements were performed with near-IR laser diodes and overtone transitions. |
