Resolution of the O3/H2O Interference Problem in Detecting Natural Tropospheric OH Via Laser Induced Fluorescence

The OH free radical has now been shown to be of pivotal importance to our understanding of tropospheric photochemistry. The laser induced fluorescence (LIF) technique has been shown to be a highly sensitive method for measuring atmospheric OH in the parts-per-quadrillion to parts-per-trillion concentration range. The high sensitivity of the LIF method, however, can be compromised by the presence of an OH interference signal resulting from the laser photolysis of in-situ O3, i.e.: followed by the very fast reaction (2), Reaction (2), in turn, is in competition with the very efficient quenching process (3).