1. Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
2. TNO (The Netherlands Organization for Applied Scientific Research), P.O. Box 6235, Eindhoven 5600 HE, The Netherlands
3. DSM Coating resins, P.O. Box 123, Waalwijk 5140 AC, The Netherlands
4. Laboratory of Physics and Physical Chemistry of Foods, Wageningen University, P.O. Box 17, Wageningen 6700 AA, The Netherlands
5. Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom