1. Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States
2. Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 01451, United States
3. Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Dresden 01328, Germany
4. U.S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, Alaska 99703, United States