Effect of Substitution Sites of the Nitro Group on UV Photodissociation of Protonated Nitrobenzimidazole Isomers oleh ZHANG Kai-lin1,2, DU Meng-ying2, XU Yi-cheng2, LI Shu-qi2, CUI Yong-liang2, ZHANG Sen2, MA Li-fu1, WANG Yan1, KONG Xiang-lei2,3