1. M. A. Subramanian and W. J. Marshall, Dupont Central Research and Development, Experimental Station, Wilmington, DE 19880-0328, USA.
2. B. H. Toby, Reactor Radiation Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
3. A. P. Ramirez, Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, NJ 07974, USA.
4. A. W. Sleight, Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
5. G. H. Kwei, Chemistry and Materials Sciences Department, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.