Detection Of Hcl At The Sub-Parts-Per-Billion Level Using Tunable Diode Laser Absorption

We report the results of a laboratory study for detecting the important atmospheric molecule, HC1, using a tunable diode laser coupled to a multipass White cell. In contrast to many such prototype studies, the calibration in this work was carried out near the concentration range of interest and verified using three independent techniques. Employing pathlengths of 40-m, we have demonstrated a detection sensitivity (S/N = 1) in the 250 - 300 parts-per-trillion range at pressures around 9 torr.