a
Department of Chemistry, University of North Carolina at Chapel Hill, Campus Box 3290, Caudill and Kenan Laboratories, Chapel Hill, USA
E-mail: mgagne@unc.edu
;
Fax: +1 919-962-2388
;
Tel: +1 919-962-0278
b
US Army Research Office, P.O. Box 12211, Research Triangle Park, USA