1. School of Chemistry, University of Manchester, Brunswick Street, Manchester M13 9PL, UK, Fax: +44‐161‐275‐4598
2. Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, UK
3. Synchrotron Radiation Department, Daresbury Laboratory, Daresbury, Warrington WA4 4AD, UK