1. Centre for Materials Science, Department of Physics, Astronomy and Mathematics, University of Central Lancashire, PR1 2HE, United Kingdom; Japan Chemical Innovation Institute, and Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552, Japan; and Department of Physics, Tohoku University, Aoba Aramaki, Aoba-ku, Sendai 980-8578, Japan