通过飞秒电子-离子符合光谱研究腺嘌呤和胸腺嘧啶碱基对的电子结构。

Electronic structure of adenine and thymine base pairs studied by femtosecond electron-ion coincidence spectroscopy.

作者信息

Gador Niklas, Samoylova Elena, Smith Valoris Reid, Stolow Albert, Rayner David M, Radloff Wolfgang, Hertel Ingolf Volker, Schultz Thomas

机构信息

Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, K1A 0R6 Canada.

出版信息

J Phys Chem A. 2007 Nov 22;111(46):11743-9. doi: 10.1021/jp076800e. Epub 2007 Oct 31.

DOI:10.1021/jp076800e

PMID:17973356

Abstract

Femtosecond pump-probe spectroscopy was combined with photoelectron-photoion coincidence detection to investigate the electronic structure and dynamics of isolated adenine (A) and thymine (T) dimers and the adenine-thymine (AT) base pair. The photoelectron spectra show that pipi* and npi* states are only weakly perturbed in the hydrogen-bound dimers as compared to the monomers. For cationic base pairs with internal energies greater than 1 eV, we observed considerable cluster fragmentation into protonated monomers. This process selectively removed signals from the npi* --> n-1 ionization channel in all dimers. The photoelectron spectra are compared to time-resolved mass spectra and confirm the assignment of short-lived pipi* and npi* populations in the adenine, thymine, and mixed AT dimers.

摘要

飞秒泵浦-探测光谱技术与光电子-光离子符合探测技术相结合，用于研究孤立的腺嘌呤（A）和胸腺嘧啶（T）二聚体以及腺嘌呤-胸腺嘧啶（AT）碱基对的电子结构和动力学。光电子能谱表明，与单体相比，ππ和nπ态在氢键结合的二聚体中仅受到微弱的扰动。对于内能大于1 eV的阳离子碱基对，我们观察到相当多的团簇碎裂成质子化单体。这个过程选择性地消除了所有二聚体中nπ*→n - 1电离通道的信号。将光电子能谱与时间分辨质谱进行比较，证实了腺嘌呤、胸腺嘧啶和混合AT二聚体中短寿命ππ和nπ布居的归属。