Design of a Novel Open-Path Aerosol Extinction Cavity Ringdown Spectrometer

We describe a new open-path aerosol extinction cavity ringdown spectrometer (CRDS), which measures extinction coefficients as aerosol is drawn transversely through the optical cavity. With no inlet tubing, particle losses in the open-path CRDS due to impaction of coarse particles or evaporation of highly humidified particles in transfer lines are minimized, improving aerosol extinction measurements in dusty and humid environments. This report presents the key elements of the new open-path CRDS design as well as comparisons with a conventional closed-path CRDS and data obtained during a field study at NOAA's instrumented 300m tower in Erie, Colorado. The open-path CRDS's 1 sigma detection limit for one second averaged data was 0.05 Mm(-1), comparable to the limit of our closed-path CRDS.Copyright 2015 American Association for Aerosol Research