1. Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, Louisiana 70803
2. Department of Physics, B5, University of Liège, B-4000 Sart-Tilman, Belgium
3. Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803
4. Department of Chemistry, Missouri University of Science and Technology, University of Missouri, Rolla, Missouri 65409-0010