1. Atmospheric Chemistry, Building 313, Plant Biology and Biogeochemistry Department, Risø National Laboratory, DK-4000 Roskilde, Denmark
2. Ford Research Laboratory, SRL-3083 Ford Motor Company, Dearborn, P.O. Box 2053 Michigan 48121-2053
3. Universite Joseph Fourier I.U.T.1. Grenoble, Departement de Chimie, 39-41 Boulevard Gambetto, 3800 Grenoble, France
4. Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado 80303