1. Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
2. Nonlinear Materials Corporation, Seattle, Washiington 98109, United States
3. Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
4. Department of Chemistry, University of Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium