1. Christopher Ingold Laboratories, University College London, 20 Gordon Street, London WC1H 0AJ, U.K. (L.B., R.J.H.C.); Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, P.O. Box 1527, GR-71110 Heraklion, Greece (T.S., D.A.); and National Gallery of Athens, 1 Michalacopoulou St. GR-11528, Athens, Greece (M.D.)