[1] Lawrence Livermore Natl Lab, Nanoscale Synth & Characterizat Lab, Livermore, CA 94550 USA
[2] Karlsruhe Inst Technol, Inst Nanotechnol, D-76021 Karlsruhe, Germany
[3] Tech Univ Darmstadt, Joint Res Lab Nanomat, D-64287 Darmstadt, Germany
[4] Tech Univ Hamburg, Inst Werkstoffphys & Technol, D-21073 Hamburg, Germany
[5] Helmholtz Zentrum Geesthacht, Inst Werkstoffforsch Werkstoffmech, D-21502 Geesthacht, Germany