On the Relaxation Mechanisms of 6-Azauracil

详细信息    查看全文

• 作者：Joa虄o Paulo Gobbo ; Antonio Carlos Borin ; Luis Serrano-Andre虂s
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：May 19, 2011
• 年：2011
• 卷：115
• 期：19
• 页码：6243-6251
• 全文大小：991K
• 年卷期：v.115,no.19(May 19, 2011)
• ISSN：1520-5207

文摘

The nonadiabatic photochemistry of 6-azauracil has been studied by means of the CASPT2//CASSCF protocol and double-味 plus polarization ANO basis sets. Minimum energy states, transition states, minimum energy paths, and surface intersections have been computed in order to obtain an accurate description of several potential energy hypersurfaces. It is concluded that, after absorption of ultraviolet radiation (248 nm), two main relaxation mechanisms may occur, via which the lowest ³(蟺蟺*) state can be populated. The first one takes place via a conical intersection involving the bright ¹(蟺蟺*) and the lowest ¹(n蟺*) states, (¹蟺蟺*/¹n蟺*)_CI, from which a low-energy singlet鈥搕riplet crossing, (¹n蟺*/³蟺蟺*)_STC, connecting the ¹(n蟺*) state to the lowest ³(蟺蟺*) triplet state is accessible. The second mechanism arises via a singlet鈥搕riplet crossing, (¹蟺蟺*/³n蟺*)_STC, leading to a conical intersection in the triplet manifold, (³n蟺*/³蟺蟺*)_CI, evolving to the lowest ³(蟺蟺*) state. Further radiationless decay to the ground state is possible through a (gs/³蟺蟺*)_STC.