Three detection systems which have been developed in part at the University of Denver will be further developed and investigated in terms of their ability to determine the flux of species to and from the atmosphere. Long-path UV (LPUV) spectroscopy will be coupled with long-path IR (LPIR) spectroscopy and used to determine the fluxes of various species. A fast response in-situ total sulfur monitor will also be optimized for response speed and sensitivity. It will be used for flux studies by means of the eddy-correlation technique. Some of the flux studies will be carried out in collaboration with the NCAR ASTER facility and Argonne National Laboratory. An atmospheric pressure flow system, free radical detector has been developed which is shown to respond to concentrations of HO2 and RO2 radicals. This apparatus, named PERCA (PEroxy Radical detector using Chemical Amplification) has been shown to respond to a number of hydrocarbon and oxygenated hydrocarbon peroxy radicals up to C8. Using the PERCA, further studies will be conducted to overcome the inability to obtain stable calibrations.
