1. Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education)School of PhysicsDalian University of Technology No. 2 Linggong Road Ganjingzi District Dalian 116024 P. R. China
2. Dalian Institute of Chemical and Physics, CAS 457 Zhongshan Road Dalian 116023 P. R. China
3. Department of Materials Science and EngineeringSouthern University of Science and Technology Shenzhen 518055 P. R. China