College of Physics and Electronic Engineering, and Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, Northwest Normal University, Lanzhou 730070;
Department of Physics, Lanzhou City University, Lanzhou 730070;
College of Physics and Electronic Engineering, and Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, Northwest Normal University, Lanzhou 730070;
College of Physics and Electronic Engineering, and Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, Northwest Normal University, Lanzhou 730070;
College of Physics and Electronic Engineering, and Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, Northwest Normal University, Lanzhou 730070;