1. Materials
Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370, United States
2. Technical
University of Vienna, Institute of Applied Physics, Wiedner Hauptstrasse
8-10, A-1040 Vienna, Austria
3. National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom
4. National
ESCA and Surface Analysis Center for Biomedical Problems, Departments
of Chemical Engineering and Bioengineering, University of Washington, Seattle, Washington 98195-1653, United States