1. National Renewable Energy Laboratory, Golden, CO 80401, USA
2. Department of Physics, Colorado School of Mines, Golden, CO 80401, USA
3. Department of Structure and Dynamics of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
4. Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401, USA