Sincrotrone Trieste, in Area Science Park, I-34012 Basovizza (Trieste), Italy.
J Phys Chem A. 2010 Sep 23;114(37):10270-6. doi: 10.1021/jp105062c.
The core level photoabsorption spectra of the nucleobases cytosine and uracil in the gas phase have been measured and the results interpreted with theoretical calculations using an ab initio Green’s function approach. A single tautomer of uracil is populated, in agreement with previous work, while three tautomers of cytosine are clearly identified, whose identity and relative populations at the temperature of the experiment were reported previously. The second-order ADC approach to polarization propagator was employed in calculations of X-ray photoabsorption energies and intensities. The theoretical spectra have been constructed as Boltzmann-factor-weighted sums of individual tautomer spectra. These theoretical spectra are in good agreement with the experimental photoabsorption results at the oxygen, nitrogen, and carbon edges. In addition we report resonant Auger spectra of the valence band of cytosine, which support previous assignments of the character of the valence band states.
已测量并解释了气相中碱基胞嘧啶和尿嘧啶的核心级光吸收光谱，使用从头算格林函数方法进行理论计算。与之前的工作一致，只生成了尿嘧啶的单个互变异构体，而明确鉴定出了胞嘧啶的三个互变异构体，之前已报道了其身份和在实验温度下的相对丰度。二阶 ADC 极化传播子方法用于计算 X 射线光吸收能量和强度。理论光谱被构建为单个互变异构体光谱的玻尔兹曼因子加权和。这些理论光谱与氧、氮和碳边缘的实验光吸收结果非常吻合。此外，我们还报告了胞嘧啶价带的共振俄歇光谱，这支持了先前对价带态性质的分配。
