[1] Natl Ctr Nanosci & Technol, CAS Ctr Excellence Nanosci, CAS Key Lab Nanosyst & Hierarch Fabricat, Beijing 100190, Peoples R China
[2] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
[3] Univ Sci & Technol Beijing, 30 Xueyuan Rd, Beijing 100083, Peoples R China
[4] Natl Ctr Nanosci & Technol, CAS Key Lab Standardizat & Measurement Nanotechno, Beijing 100190, Peoples R China