1. Joseph Henry Laboratories of Physics, Department of Physics, Princeton University, Princeton, NJ 08544, USA.
2. Princeton Center for Complex Materials, Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA.
3. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94305, USA.
4. Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland.
5. Physik-Institut, Universität Zürich-Irchel, 8057 Zürich, Switzerland.