1. Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow, G1 1XL, U.K., Department of Pure and Applied Physics, University of Strathclyde, Colville Building, North Portland Street, Glasgow, G1 1XN, U.K., and Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, U.K.