**Acknowledgements**

We sincerely appreciate the supports from the Analytical Instrumentation Facility (AIF) and the Wilson College of Textiles, North Carolina State University, USA. We acknowledge the technical advice from Anton Jansson (Ex-Postdoctoral Research Scholar, AIF). This work was performed in part at the Analytical Instrumentation Facility (AIF) at North Carolina State University, which is supported by the State of North Carolina and the National Science Foundation (award number ECCS-1542015). The AIF is a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), a site in the National Nanotechnology Coordinated Infrastructure (NNCI).
