1. Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstr. 5–13 81377 Munich Germany
2. Institut Laue-Langevin BP 156 F-38042 Grenoble Cedex 9 France
3. Centre for Science At Extreme Conditions and School of Chemistry University of Edinburgh Peter Guthrie Tait Road EH9 3FD Edinburgh UK