1. Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
2. Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
3. SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
4. Bruker BioSpin Corporation, Billerica, Massachusetts 01821, United States