1. Central Laser Facility, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 OQX, United Kingdom (M.T., A.W.P., K.L.R.); Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom (K.F.B., J.M.C.); Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom (P.R.R.); and Synchrotron Radiation Source, Science & Technology Facilities Council, Daresbury...