HIGH RESOLUTION ELECTRON IMPACT IONISATION STUDIES FOR OZONE AND OClO MONOMERS AND DIMERS G Denifl*, D Muigg*, N J Mason=86, A Stamatovic=A7 and T D M=E4rk*, * Institut fur Ionenphysik, Leopold Franzens Universitat, Technikerstrasse 25, A-6020, Innsbruck, Austria =86 Molecular Physics Laboratory, Dept. of Physics and Astronomy, UCL, Gower Street, London WC1E 6BT, UK =A7 Faculty of Physics, Beograd, P.O.Box 368, 11001, Beograd, Yugoslavia The first electron impact ionisation experiments upon the atmospheric dimers (O3)2 and (OClO)2 are reported. Appearance energies for product cations are reported and the bond energies for the cationic dimers deduced.