1. Department of Chemistry, Department of Electrical and Computer Engineering, NSF ERC for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, Colorado 80523, Beijing National Laboratory for Molecular Science, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Haidian, Beijing 100080, China, and National Center of Nanoscience and Technology, Beijing 100080, People's Republic of China