NOy

The instrument has lower power, size, weight, and vacuum requirements than a chemiluminescence-based instrument while approaching its sensitivity, precision and time response. In the NOy CRDS instrument of the present invention, NOy and its components are converted into NO2 by thermal decomposition (TD) in a fused silica inlet (henceforth referred to as quartz, following convention), followed by the addition of ozone to convert NO to NO2. NO2 is then measured using a cavity ring-down spectroscopy instrument, utilizing a 405 nm laser. The device may comprise four parallel channels, each driven by the same laser, to measure NO, NO2, NOy and O3, respectively, such that overall NOy may be measured, as well as its components NO, NO2, as well as ozone (O3).