1. Institute for Ecological Chemistry, GSFNational Research Center for Environment and Health, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany, Stanford Linear Accelerator Center, Stanford Synchrotron Radiation Laboratory, MS 69, 2575 Sand Hill Road, Menlo Park, California 94025, ExxonMobil Research and Engineering Company, Route 22 East, Annandale, New Jersey 08801, and Department of Chemistry, The University of Arizona, Tucson, Arizona 85721