Bonded Excimer in Stacked Cytosines: A Semiclassical Simulation Study. (22nd February 2015)

• Record Type: Journal Article
• Authors: Wu, Weifeng; Yuan, Shuai; She, Jiajie; Dou, Yusheng; Allen, Roland E.
• Other Names: Li Fuli Academic Editor.
• Is Part Of: International journal of photoenergy. Volume 2015(2015)
• Publication Date: 2015-02-22
• Subjects: Photochemistry -- Periodicals; Photobiology -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Photochimie; Photobiologie; Chimie physique et théorique; Chemistry, Physical and theoretical; Photobiology; Photochemistry; Electronic journals; Periodicals; 541.35
• DOI: 10.1155/2015/937474
• Languages: English
• ISSNs: 1110-662X

Abstract

Abstract : The formation of a covalent bond between two stacked cytosines, one of which is excited by an ultrafast laser pulse, was studied by semiclassical dynamics simulations. The results show that a bonded excimer is created, which sharply lowers the energy gap between the LUMO and HOMO and consequently facilitates the deactivation of the electronically excited molecule. This is different from the case of two stacked adenines, where the formation of a covalent bond alters the nonadiabatic deactivation mechanism in two opposite ways. It lowers the energy gap and consequently leads to the coupling between the HOMO and LUMO levels, thus enhancing the deactivation of the electronically excited molecule. On the other hand, it leads to restriction of the deformation vibration of the pyrimidine in the excited molecule, because of a steric effect, and this delays the deactivation process of the excited adenine molecule with return to the electronic ground state.