1. Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
2. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
3. Bruker BioSpin, Billerica, Massachusetts 01821, USA
4. Weizmann Institute of Science, Rehovot, Israel
5. NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands