Wiss. Ass. (Heidelberg 1963-1967)
Post-Doc Advanced Study Program National Center of Atmospheric Research (Boulder/USA 1964-1965)
Visiting Scholar National Center of Atmospheric Research (Boulder/USA 1965-1967)
Akad. Rat (Heidelberg 1967-1969)
Senior Scientist National Center of Atmospheric Research (Boulder/USA 1969-1974)
o. Professor für Geophysik (Köln 1974-2000)
Direktor Institut für Physikalische Chemie Kernforschungsanlage Jülich/Institut für Chemie Kernforschungsanlage Jülich, Institut 3: Atmosphäre Chemie (Jülich 1976-2000)
Affiliate Scientist National Center of Atmospheric Research (Boulder/USA 1997-2007)