1. Natural Sciences and Engineering Research Council of Canada postdoctoral fellow, AT&T Bell Laboratories, Murray Hill, New Jersey 07974.
2. Member of the technical staff in the Physical and Inorganic Chemistry Department, AT&T Bell Laboratories, Murray Hill, New Jersey 07974.
3. Member of the technical staff in the Condensed State Physics Department, AT&T Bell Laboratories, Murray Hill, New Jersey 07974.
4. Head of the Chemical Physics Department, AT&T Bell Laboratories, Murray Hill, New Jersey 07974.