[1] Univ Adelaide, Sch Chem Engn, Adelaide 5000, Australia
[2] Helmholtz Zentrum Hereon, Inst Surface Sci, D-21502 Geesthacht, Germany
[3] Australian Synchrotron, Clayton 3168, Australia
[4] Univ Wollongong, Inst Superconducting & Elect Mat, Wollongong, NSW 2500, Australia