Unified Model for the Ultrafast Decay of Pyrimidine Nucleobases

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• 作者：Manuela Merchá ; n ; Remedios Gonzá ; lez-Luque ; Teresa Climent ; Luis Serrano-André ; s ; Elena Rodr&iacute ; guez ; Mar Reguero ; Daniel Pelá ; ez
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：December 28, 2006
• 年：2006
• 卷：110
• 期：51
• 页码：26471 - 26476
• 全文大小：210K
• 年卷期：v.110,no.51(December 28, 2006)
• ISSN：1520-5207

文摘

Ultrafast decay processes detected after absorption of UV radiation in gas-phase pyrimidine nucleobasesuracil, thymine, and cytosine are ascribed to the barrierless character of the pathway along the low-lying¹(mages/gifchars/pi.gif" BORDER=0 >mages/gifchars/pi.gif" BORDER=0 >*) hypersurface connecting the Franck-Condon region with an out-of-plane distorted ethene-like conicalintersection with the ground state. Longer lifetime decays and low quantum yield emission are on the otherhand related to the presence of a ¹(mages/gifchars/pi.gif" BORDER=0 >mages/gifchars/pi.gif" BORDER=0 >*) state planar minimum on the S₁ surface and the barriers to accessother conical intersections. A unified model for the three systems is established on the basis of accuratemulticonfigurational CASPT2 calculations, whereas the effect of the different levels of theory on the resultsis carefully analyzed.