在光激活的氨酸中揭开超快的动力学
Gareth M Roberts1, Craig A Williams, Jamie D Young
1Department of Chemistry, University of Warwick, Coventry, United Kingdom.
Journal of the American Chemical Society
|June 22, 2012
概括
氨酸中的超快速动态揭示了兴奋状态路径. 研究人员使用时间解析速度图像和初始计算来绘制N-H键裂变的图像,提供了对DNA基质光化学的见解.
科学领域:
- 物理化学 物理化学
- 量子化学 是一个量子化学.
- 摄影化学的使用.
背景情况:
- 氨酸的兴奋状态动态对于理解光化学反应至关重要.
- 在N-H债券裂变中, (1) πσ* 状态的作用具有显著的意义.
- 模拟这些动态可以提供有关生物分子 (如DNA基) 的见解.
研究的目的:
- 通过实验和理论方法的结合,研究氨酸中的电子兴奋状态动态.
- 阐明控制N-H键裂变的光化学路径和形交叉点.
- 为了建立一个基础,模拟类似的动态在纯素衍生DNA基的基础.
主要方法:
- 超快速的时间分辨率速度图像绘制 (TR-VMI) 来探测动态.
- 完整的活跃空间自相一致场 (CASSCF) 开始计算用于理论研究.
- 宽带 femtosecond 激光脉冲用于波长范围内的激发.
主要成果:
- 在250nm以上的激发没有显示 (1) πσ*驱动的N-H键裂变.
- 在250和240 nm之间,合到 (1) πσ* 状态,在<1 ps. 中促进了N-H 键裂变.
- 激发到更高的 (1) ππ* 状态导致了连续动态,包括 (1) πσ* 和 N-H 键裂变在 155 ± 30 fs (240 nm) 和 170 ± 20 fs (200 nm) 中.
结论:
- 这项研究全面地绘制了阿尼林的光化学路径和形交叉点.
- CASSCF的计算揭示了素的状交叉形状与关氨酸的氨基部分之间的相似之处.
- 这些发现为理解DNA基的 (1) πσ*驱动动力学提供了强有力的基础.
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