1. School of Physics Xidian University Xi'an 710071 China
2. NanoEngineering Group Faculty of Mechanical Engineering Technion‐Israel Institute of Technology Haifa 3200003 Israel
3. Department of Bioproducts and Biosystems School of Chemical Engineering Aalto University P. O. Box 16300 Aalto Espoo FI‐00076 Finland
4. Departments of Chemical and Biological Engineering Chemistry and Wood Science Bioproducts Institute The University of British Columbia 2360 East Mall Vancouver BC V6T 1Z3 Canada