1. Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23185, USA
2. Air Force Research Laboratory, Space Vehicles Directorate, 3550 Aberdeen Avenue SE, Bldg 570, Kirtland Air Force Base, New Mexico 87117-5-776, USA
3. Institute for Scientific Research, Boston College, Boston, Massachusetts 02467, USA
4. Laser-Laboratorium Göttingen, Hans-Adolf-Krebs-Weg 1, D-37077 Göttingen, Germany
5. Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany
6. Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, D-37077 Göttingen, Germany