[1] Fudan Univ, State Key Lab Surface Phys, Shanghai 200433, Peoples R China
[2] Fudan Univ, Dept Phys, Shanghai 200433, Peoples R China
[3] Fudan Univ, Key Lab Micro & Nano Photon Struct, Minist Educ, Shanghai 200433, Peoples R China
[4] Fudan Univ, Dept Macromol Sci, State Key Lab Mol Engn Polymers, Shanghai 200433, Peoples R China
[5] Bar Ilan Univ, Dept Phys, IL-52900 Ramat Gan, Israel
[6] Bar Ilan Univ, Inst Nanotechnol, IL-52900 Ramat Gan, Israel