Disentangling Intrinsic Ultrafast Excited-State Dynamics of Cytosine Tautomers

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• 作者：Jr-Wei Ho ; Hung-Chien Yen ; Wei-Kuang Chou ; Chih-Nan Weng ; Li-Hao Cheng ; Hui-Qi Shi ; Szu-Hsueh Lai ; Po-Yuan Cheng
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：August 4, 2011
• 年：2011
• 卷：115
• 期：30
• 页码：8406-8418
• 全文大小：1323K
• 年卷期：v.115,no.30(August 4, 2011)
• ISSN：1520-5215

文摘

Gas-phase ultrafast excited-state dynamics of cytosine, 1-methylcytosine, and 5-fluorocytosine were investigated in molecular beams using femtosecond pump鈥損robe photoionization spectroscopy to identify the intrinsic dynamics of the major cytosine tautomers. The results indicate that, upon photoexcitation in the first absorption band, the cytosine enol tautomer exhibits a significantly longer excited-state lifetime than its keto and imino counterparts. The initially excited states of the cytosine keto and imino tautomers decay with sub-picosecond dynamics for excitation wavelengths shorter than 300 nm, whereas that of the cytosine enol tautomer decays with time constants ranging from 3 to 45 ps for excitation between 260 and 285 nm.