Investigation of airborne particles by on line single particle mass spectrometry with novel ionization approaches This works objective was to develop new ionization methods to enable the detection of organic inorganic pollutants from single airborne particles. For the first time the universal laser desorption ionization was successfully combined with the selective resonance enhanced multiphoton ionization. This facilitates the analysis of the distribution of hazardous PAHs on single particles and conventional methods of source apportionment according to particle size. Significant progress in the development of single particle analysis and the understanding of atmospheric particles could be achieved.<eng>