1. Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
2. Division of Biomedical Engineering, School of Engineering, College of Science and Engineering, University of Glasgow, Glasgow G12 8LT, U.K.
3. Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, U.K.
4. Diamond Light Source Ltd., Diamond House, Harwell
Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.