1. Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600
MB, Eindhoven, The Netherlands
2. Instituto de Ciencia Molecular, Universidad de Valencia, C/Catedrático J. Beltrán
2, ES-46980 Paterna (Valencia), Spain
3. Advanced Materials Research Center, Nippon Shokubai Co., Ltd., 5-8 Nishi Otabi-cho, Suita,
Osaka 564-8512, Japan