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Laser mass spectrometry for the simultaneous detection of molecules, radicals, soot precursor particles and of primary soot. The method is used to elucidate reaction pathways of soot formation and to monitor pollutants in technical exhaust systems

Mobiles Laser-Massenspektrometer im Einsatz zur Abgasmessung an einem Motorroller

The group is engaged in both fundamental and applied research. This includes:

1. the elucidation of soot formation mechanisms
2. the analysis of pollutants in automobile exhaust gas

With regard to the first problem, we have been able to show that soot formation involves two types of precursor particles that are entirely different. One type consists of stacked pericondensed polyaromatic compounds characterised by a minimum number of edge positions. The structure of the other type is the subject of current research.
In our work on exhaust gas analysis, we address problems such as the potential influence of (biogenic) fuel additives or the dependence of soot reactivity on engine operating conditions. Soot reactivity is an important aspect for diesel particle filter regeneration.
Reflectron time-of-flight mass spectrometers have proved very useful in this research, as they exhibit several advantages when combined with photo ionization. These include:

• wide mass range from atoms/molecules and soot precursor particles to young soot (approx. one million atomic mass units)
• high resolution
• high sensitivity to aromatic compounds when using multiphoton ionization