1. Section for Chemical Reactivity, Environmental Science and Technology Department, Risø National Laboratory, DK-4000 Roskilde, Denmark
2. Ford Motor Company, Ford Research Laboratory, SRL-E3083, Dearborn, P.O. Box 2053, Michigan 48121-2053
3. Ford Motor Company, Ford Forschungszentrum Aachen, Dennewartstrasse 25, D-52068 Aachen, Germany