In chemiluminescence analyzers, what happens to NOx in the sample gas?

In chemiluminescence analyzers, nitrogen oxides (NOx), which primarily include nitric oxide (NO) and nitrogen dioxide (NO2), undergo a specific process where nitric oxide is oxidized to nitrogen dioxide. Following this oxidation, the NO2 can react with excess ozone (O3) within the analyzer's detection chamber to produce excited-state nitrogen dioxide molecules. When these excited molecules return to their stable state, they release energy in the form of light—a process known as chemiluminescence.

The significance of the conversion of NO to nitrogen gas (N2) in this context aligns with the principle of measuring total NOx emissions. While the analyzer detects the light emitted during the reaction, the transformation of NO to N2 is critical, as it effectively measures the concentration of nitrogen oxides present in the sampled gas. This process highlights the role of oxidation in detecting NOx levels accurately, which is essential for understanding emissions and compliance with environmental regulations.

The other options involve processes that do not accurately describe the behavior of NOx in a chemiluminescence analyzer. For instance, oxidation to carbon dioxide does not occur with NOx; dissolution in a liquid medium is not how these analyses operate; and conversion to particulate matter