1. Department of Chemistry and Biochemistry, Humboldt Centre for Nano- and Biophotonics, Institute for Light and Matter, Greinstrasse 4-6, 50939 Cologne, Germany
2. Centre for Photonics and Photonic Materials, Department of Physics
3. University of Bath
4. Department of Chemistry and Biochemistry, Institute of Organic Chemistry, Greinstrasse 4, 50939 Cologne, Germany
5. Centre of Biophotonics, SUPA School of Physics and Astronomy
6. University of St Andrews