A laser based procedure for the detection of atmospheric NOx gases

It has been known for some time that the combustion of fossil fuels, biomass burning and the automobile, have principally lead to the increased presence of NOX (x=1,2) in the atmosphere especially in the urban environment. The average concentrations of NOX in American, European cities and specifically in Glasgow is about 35 ppb. A laser based procedure, using ionization chambers, has been developed, which will detect NO down to sub ppb levels and NO2 to a few parts per billion. A number of wavelengths can be used but a three photon process at 380 nm is likely to be the most sensitive and selective wavelength for this analysis. This procedure can also be used for a number of other urban pollutants with a single laser operating in the range 200–400 nm.