[1] Xiamen Univ, Dept Phys, State Key Lab Phys Chem Solid Surface, Xiamen 361005, Peoples R China
[2] Xiamen Univ, Dept Commun Engn, State Key Lab Phys Chem Solid Surface, Xiamen 361005, Peoples R China
[3] Univ Rochester, Dept Radiol, Rochester, NY 14642 USA