1. Department of Chemistry, National University of Ireland - Maynooth, Maynooth, County Kildare, Ireland, Laboratoire Francis Perrin, CEA/DSM/IRAMIS/SPAM CNRS URA 2453, CEA Saclay, 91191 Gif-sur-Yvette, France, and Laboratoire de PhotoPhysique Moléculaire, CNRS UPR 3361, Bât. 210- Université Paris-Sud 11, F91405 Orsay Cedex, France