Direct measurement of NO2 in the marine atmosphere by laser-induced fluorescence technique

A simple and compact instrument for NO₂ measurement by laser-induced fluorescence (LIF) technique with a pulsed solid state laser and a multi-pass excitation system was developed and optimized for several conditions. As a result of laboratory experiment, the limit of detection (LOD) reached 94 pptv for 60 s integration. It was thought that an LIF instrument with this LOD value would be capable of quantifying sub-ppbv NO₂ in unpolluted marine atmosphere. As the second step, a field test of the instrument was conducted in the marine atmosphere at Cape Hedo, Okinawa Island, Japan, in summer 1999. Intercomparison between the LIF instrument and a chemiluminescence detector with a photolytic converter (PLC-CL) was also made in this test. Consequently, the LIF instrument was shown to be of practical use for measuring NO₂ in clean maritime air.