We would like to acknowledge partial support by the Division of Chemical Sciences, Office of Basic Energy Sciences, Office of Energy research, U.S. Department of Energy, the Greek Ministry of Research and Technology (PENED91 and PENED95 grants), the International Atomic Energy Agency and the EU (HCM grant). We would also like to thank Nico Stolterhoft of the HMI-Berlin for his generous support and interest in this project. Finally, T.J.M.Z. and E.M.B. would also like to thank Mohammad Abdallah, Kevin Carnes, Paul Gibson, Bob Geering, Bob Krauss, Al Rankin, Mark Ross and Mike Wells of the J.R. Macdonald laboratory at Kansas State University for their invaluable technical assistance and help during their stay there.