Das Projekt "Direkte Untersuchungen troposphaerischer Reaktionen von Alkoxy-Radikalen" wird vom Umweltbundesamt gefördert und von Universität-Gesamthochschule Essen, Fachbereich 8 Chemie, Institut für Physikalische und Theoretische Chemie durchgeführt. The oxidation of hydrocarbons in the troposhere is of major importance when dealing with photochemical ozone formation. Therefore this project is focussed on the reactivity of RO-radicals of C3-C6-hydrocarbons towards O2 and NO2 as well as the thermal decomposition and the isomerization of these RO-radicals. The received data shall be evaluated by simulation under consideration of complete reaction mechanisms. The NO/NO2 condersion factors (NOCON-factors) obtained by this method reflect the mechanistic quota of the ozone formation potential of these hydrocarbons. The present investigations are limited to select Alkoxy-radicals with typical structural differences, i.e. 1-Alkoxy, 2-Alkoxy, i-Alkoxy, cycl.-Alkoxy. For these species absolute and relative rate constants can be determined by time-resolved studies of OH and NO2. In order to strengthen the comprehension of the measured rate constants and in order to transfer these data to other RO-radicals that are not yet investigated theoretical studies will be made. These studies are based on RRKM-calculations with determination of structural parameters of transition states by Gaussian 92 ab inition calculations.