Mass Spectrometry Group

 Molecular Beam Mass Spectrometry (MBMS) - probing
zum Bild Molecular Beam Mass Spectrometry (MBMS) - probing

Modern molecular beam mass spectrometry (MBMS) is an optimal instrument for tracing various chemical species in stationary combustion processes. The mass spectrometry group operates two MBMS systems optimized for the investigation of gas-phase reactions and characterization of combustion characteristics of different (alternative) fuels.

Molecular Beam Mass Spectrometry (MBMS) is an analytical technique for determining the molecular weight of molecules sampled from a reactive environment. Gases are probed in-situ and the sample is expanded into a molecular beam. Thus, chemical reactions are quenched immediately and the sample composition is "frozen". Even highly reactive species, such as radicals, are preserved by this sampling technique and are detectable.  The subsequent mass spectrometric analysis allows for the separation of species by their individual molecular weight.

The combination of molecular beam sampling with a time-of-flight mass spectrometer (TOF) provides multiple advantages:

  • Simultaneous detection of almost all species relevant to combustion
  • Detection of free radicals and other high reactive species
  • Detection of the entire mass range from the molecular gas phase up to particles in the nanometer range
  • High repetition rate: up to 40,000 mass spectra per second
  • Selective detection due to the use of photo ionization techniques

The group operates two mass spectrometers with different focus:

  1. A mobile Photo Ionization Mass Spectrometer (PIMS) optimized for detection of (nano) particulate matter
  2. High temperature flow reactor with MBMS detection for validation of gas phase reaction kinetics

The group was formed in 2012 and deals with chemical questions in the topics fuels, pollutants and gasification. The group operates between the departments of chemical kinetics and combustion laser diagnostics and combines the activities through MBMS experiments. The given tasks range from fundamental kinetical research such as the experimental analysis of chemical reactions networks in reactive environments of combustion, gasification and pyrolysis processes up to exhaust gas measurements on technical test rigs focusing on nano particulate matter.

Dr. rer. nat. Markus Köhler
German Aerospace Center

Institute of Combustion Technology

Tel: +49 711 6862 756

Fax: +49 711 6862-578

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