1. Central Research Laboratories, Idemitsu Kosan Co., Ltd., 1280 Kamiizumi, Sodegaura 299-0293, Japan, Institute for Energy Utilization, National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba 305-8569, Japan, and Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439