A new approach for fast, simultaneous NO/NO₂ analysis: Application of basic features of multiphoton-induced ionization and dissociation of NO_x

A new method of simultaneously recording NO and NO₂ concentrations in complex gas mixtures is described. This method is based on resonance enhanced multiphoton ionization (REMPI), on time-of-flight mass analysis, and on monitoring the kinetic energy released upon dissociation of NO₂. Its benefits are high speed and high flexibility. NO/NO ₂ analysis can therefore be combined with the simultaneous monitoring of other components. For instance, NH₃ is a compound of interest when studying the chemical reactions of NO_x in catalytic converters of combustion engines. The spectroscopic excitation schemes used for this new method are discussed in detail. Its reliability has been demonstrated by performing measurements at an industrial motor test facility. This novel technique performs well in comparison with conventional NO_x analysis using chemiluminescence detection. [Figure not available: see fulltext.].