1. Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, School of Biological Sciences, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom, and Laboratoire de Spectrochimie Infrarouge et Raman, CNRS LP 2631, Université des Sciences et Technologies de Lille, Bât. C5, 59655 Villeneuve d'Ascq Cedex, France