1. A. R. Ravishankara is in the Atmospheric Chemical Kinetics Program, Aeronomy Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80303, USA;
2. G. Hancock is in the Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 2QZ, UK;
3. M. Kawasaki is in the Department of Molecular Engineering, Kyoto University, Kyoto 606-8501, Japan;
4. Y. Matsumi is at the Solar Terrestrial Environmental Laboratory and Graduate School of Science, Nagoya University, 3–13, Honohara, Toyokawa 442-8507, Japan.