国家自然科学基金20703016;湖南省科技计划2010FJ6030;固体表面物理化学国家重点实验室厦门大学开放课题经费资助The project was supported by the National Natural Science Foundation of China20703016;Scientific and Technological Projects of Hunan Province,China2010F J6030;State Key Laboratory for Physical Chemistry of Solid Surface;China