1. Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
2. Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
3. Department of Chemistry and Department of Physics and Astronomy, Rice University, Houston, Texas 77251-1892, USA and Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
4. Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA