1. Institute for Molecules and Materials, Radboud University, Heijendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
2. Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
3. School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K.
4. Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.