1. Université Pierre et Marie Curie and Institut de Physique du Globe de Paris, 75252 Paris, France.
2. Bayerisches GeoInstitut, 95440 Bayreuth, Germany.
3. Laboratoire de Sciences de la Terre, Ecole Normale Supérieure de Lyon, 69364 Lyon, France.
4. School of Physics and Centre for Science at Extreme Conditions, University of Edinburgh, EH9 3JZ, UK.
5. European Synchrotron Radiation Facility, 38043 Grenoble, France.