1. Faculty of Engineering Baden‐Württemberg Cooperative State University Karlsruhe 76133 Karlsruhe Germany
2. Institute of Inorganic Chemistry Karlsruhe Institute of Technology 76131 Karlsruhe Germany
3. Department of Optical Nanoscopy Max Planck Institute for Medical Research 69120 Heidelberg Germany
4. Laboratory for Electron Microscopy Karlsruhe Institute of Technology 76131 Karlsruhe Germany
5. Bruker BioSpin MRI GmbH Preclinical Imaging Division 76275 Ettlingen Germany
6. Department of Physics Lafayette College Easton PA 18042 USA