کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5375905 | 1504311 | 2008 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Elucidating ultrafast nonradiative decay of photoexcited uracil in aqueous solution by ab initio molecular dynamics
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
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چکیده انگلیسی
Nonradiative decay of the photoexcited RNA base uracil has been studied in fully explicit aqueous solution using nonadiabatic ab initio molecular dynamics. Detailed comparison of the time-dependent nonadiabatic transition probability with specific molecular vibrational motions provides insight into the mechanism of the ultrafast internal conversion. From a monoexponential fit to the excited state ensemble population, the lifetime of the first electronically excited ÏÏâ singlet state has been determined to be 359Â fs. Additional, reference, nonadiabatic simulations have been carried out in the gas phase, pinpointing the effects of the solvent on the photophysics of uracil. The gas phase excited state lifetime is calculated to be 608Â fs, somewhat longer than in solution. In terms of excitation energies and geometrical parameters, the differences between gas phase and aqueous solution are found to be generally small. A notable exception is the excited state out-of-plane torsional motion about the CC double bond, which appears severely damped by the solvent. Moreover, hydrogen bond interactions between the uracil oxygens and the solvent hydrogens are seen to enhance internal conversion.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Physics - Volume 347, Issues 1â3, 23 May 2008, Pages 405-412
Journal: Chemical Physics - Volume 347, Issues 1â3, 23 May 2008, Pages 405-412
نویسندگان
Harald Nieber, Nikos L. Doltsinis,