1. Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, U.K.
2. ISIS, STFC, Rutherford Appleton
Laboratory, Chilton, Didcot, Oxon OX11 0QX, U.K.
3. Unilever Research and Development
Laboratory, Port Sunlight, Quarry Road
East, Bebington, Wirral CH63 2JW, U.K.