1. School of Chemistry, University of St. Andrews, Purdie Building, St. Andrews KY16 9ST, U.K.
2. ICGM, Université de Montpellier, CNRS, ENSCM, Montpellier 75005, France
3. Defence Science and Technology Laboratory (Dstl), Porton Down, Salisbury, Wiltshire SP4 0JQ, U.K.
4. Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, U.K.
5. Department of Physical and Macromolecular Chemistry, Faculty of Sciences, Charles University, Hlavova 8, 128 43 Prague 2, Czech Republic