The ac Stark shifts of the terahertz clock transitions of barium

Yu Geng-Hua†^a), Geng Ying-Ge^a), Li Long^a), Zhou Chao^a), Duan Cheng-Bo^b), Chai Rui-Peng^a), Yang Yong-Ming^a)

Simplified energy level diagram of barium and some possible transitions between the metastable states and the higher atomic states.