1. Material Research Centre, Indian Institute of Science, Bangalore 560012, India
2. Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic
3. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
4. Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
5. School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
6. Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
7. CAESR, Department of Physics, University of Oxford, The Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
8. Department of Physics, University of California, Berkeley, California 94720, United States
9. Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, Avenida de los Castros s/n, E-39005 Santander, Spain