Charge state effect on the K-shell ionization of iron by xenon ions near the Bohr velocity * Zhou Xian-Ming(周贤明) a) , Zhao Yong-Tao(赵永涛) a) † , Ren Jie-Ru(任洁茹) a)b) , Cheng Rui(程 锐) a) , Lei Yu(雷 瑜) a) , Sun Yuan-Bo(孙渊博) a) , Xu Ge(徐 戈) a)b) , Wang Yu-Yu(王瑜玉) a) , Liu Shi-Dong(刘世东) a)b) , and Xiao Guo-Qing(肖国青) a) a)