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 94pptv for 60s 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.