1. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
2. Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA.
3. Physics Department, University of California, Davis, CA 95616, USA.
4. Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433, USA.
5. National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.