1. Laboratoire de Chimie Université de Lyon Ecole Normale Supérieure de Lyon Université Claude Bernard Lyon 1 CNRS UMR5182 Lyon 69364 France
2. Electrooptical Systems Swedish Defence Research Agency (FOI) Linköping SE‐581 11 Sweden
3. Air Force Research Laboratory Dayton OH 45433 USA
4. Department on Physics Norwegian University of Science and Technology Trondheim NO‐7491 Norway