[1] Tech Univ Berlin, Dept Chem Funct Mat, D-10623 Berlin, Germany
[2] Tech Univ Berlin, Dept Chem, D-10623 Berlin, Germany
[3] Univ Freiburg, Inst Anorgan & Analyt Chem, D-79104 Freiburg, Germany
[4] Tech Univ Berlin, Ctr Elect Microscopy ZELMI, D-10623 Berlin, Germany