1. Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus, Denmark, Department of Chemistry, The University of New Mexico, Albuquerque, New Mexico 87131, The Institute of Photographic Chemistry, Chinese Academy of Sciences, Dewai, Beishatan, Beijing 100101, PRC, and The Swedish National Testing and Research Institute, Box 857, S-50115 Borås, Sweden