Time-resolved chemical analysis by laser mass spectrometry: Monitoring of in-cylinder and catalytic-converter processes of combustion engines

A laser mass spectrometer (LAMS) for simultaneous detection of NO, NO ₂, NH₃ and other components (N₂O, CO, O ₂, H₂O, aromatics) in the exhaust of combustion engines is presented. Its temporal resolution is in the 10 ms range. Comparison with non-dispersive IR, flame ionisation detection and chemical luminescence detection have been performed. Emissions of Otto and Diesel engines have been studied at different velocities, load and three sampling positions: in front of a catalytic pre-converter, in front and after the main catalytic converter. Finally, NO, CO, H₂O, toluene and O₂ were detected within the cylinder in dependence on the crank angle with a time resolution in the 10 ms range.