1. Almaden Research Center, IBM Research Division, 650 Harry Road, San Jose, California 95120, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Display Technology, IBM Japan, 1623-14 Shimotsuruma, Yamato-shi, Kanagawa-ken 242, Japan, and Materials Laboratory, IBM Japan, 1 Kirihara-cho, Fujisawa-shi, Kanagawa-ken 252, Japan