* Corresponding authors

^a College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, China
E-mail: cyzhang@sdnu.edu.cn
Fax: +86-0531-82615258
Tel: +86-0531-86186033

^b Institute of Materials Research and Engineering, 2 Fusionopolis Way, Singapore

^c Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams (Ministry of Education), School of Physics, Dalian University of Technology, Dalian 116024, China
E-mail: yrfang@dlut.edu.cn

^d Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore

^e College of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006, China
E-mail: niweihai@suda.edu.cn