The generation of "prompt" (Fenimore) NO has been established experimentally with high and low pressure flames and a variety of fuels.  The mechanism for formation of prompt NO is moderately well understood, as modeling results are in general agreement with experimental results.  However, there are several questions that remain, including the determination of the role C-H performs in the prompt NO mechanism.  The formation of NO is intertwined with the production of soot in combustion processes. Current research is focused on determining the exact role C-H plays in the prompt NO mechanism and the formation of nitrogen heterocycles in soot.