Emissions of Carbon Monoxide (CO) from anthropogenic sources, in particular automobile exhaust, exceed in quantity the mass of all other man-made source pollutants combined. Because of its photochemical lifetime and insolubility, CO is an exceptional tracer to examine polluted air masses. By meas... Show moreEmissions of Carbon Monoxide (CO) from anthropogenic sources, in particular automobile exhaust, exceed in quantity the mass of all other man-made source pollutants combined. Because of its photochemical lifetime and insolubility, CO is an exceptional tracer to examine polluted air masses. By measuring CO fluxes, the amount of air pollutants that originate from anthropogenic and biogenic sources can be traced. A commonly used instrument for detecting CO is the vacuum ultra-violet (VUV) fluorescence analyzer. This project focused on modifying and redesigning the NCAR Research Aviation Facility’s (RAF) VUV fluorescence analyzer to improve both its sensitivity to CO and its signal to noise ratio. The RAF VUV fluorescence analyzer has proven sensitive enough to measure CO mixing ratios, however it was not sensitive enough to measure CO fluxes. The instrument’s flow cell and its fluorescence detector, a photomultiplier tube (PMT), were both examined for ways to improve the sensitivity to CO and the signal to noise ratio. The flow cell was modified to reduce photon scattering and then later redesigned to reduce both photon and air molecule leaks. A new PMT was also selected to improve the instrument’s detection limit. Delivery of the new flow cell and the new PMT was delayed past the end of this project. Because of this, new instrument measurements and analysis could not be completed. However, it was expected that these modifications would result in improvements to the instrument’s sensitivity to CO and signal to noise ratio when these parts arrive. Show less
