Optical absorption of isolated silver cluster-tryptophan: A joint experimental and theoretical study T. Tabarin, R. Antoine, I. Compagnon, M. Broyer, P. Dugourd, R. Mitrić, J. Petersen and V. Bonačić-Koutecký Eur. Phys. J. D, 43 1-3 (2007) 275-278 Published online: 24 May 2007 DOI: 10.1140/epjd/e2007-00118-5