On the development and validation of FAGE for local measurement of tropospheric OH and HO2

Abstract

A fluorescence assay by gas expansion (FAGE) instrument based on laser-induced fluorescence designed both for laboratory validation studies and for field meaasurements of OH and HO2 is described. Laboratory validation centers around the development of techniques for assessing interference from O3 photolysis and calibration of the OH signal. Calibration is centered on discharge flow and water photolysis. Optimization of the experiment relies on detailed photochemical modeling, and the proposed techiques are discussed. Attention is also paid to the possible effects of the supersonic flow field on the fluorescence assay, and the feasibility of developing a computational fluid dynamics model is discussed. -from Authors