Synchrotron radiation has been used to record for the first time absolute vacuum ultraviolet photoabsorption cross-sections of trifluoroacetic acid (TFA) and chlorodifluoroacetic acid (CDFA) in the 4.5–10.8 eV energy range. In order to further our knowledge of the major electronic transitions and thus help interpret the photoabsorption data, theoretical calculations using time-dependent density functional theory (TD-DFT) level have been performed. These calculations have provided important information on the nature of the excited electronic states which have been assigned to valence, mixed valence-Rydberg and Rydberg transitions. Due to the lack of any information about CDFA ionic states, we also provide Equation-of-Motion Coupled-Cluster Single and Doubles (EOM-CCSD) vertical ionisation energies. Photolysis lifetimes in the Earth's atmosphere for both chemical compounds have also been estimated from the absolute photoabsorption cross-section data.

中文翻译：

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三氟乙酸和氯二氟乙酸在 4.5 – 10.8 eV 光子能量区的电子光谱


同步辐射首次用于记录三氟乙酸 （TFA） 和氯二氟乙酸 （CDFA） 在 4.5–10.8 eV 能量范围内的绝对真空紫外光吸收截面。为了进一步了解主要的电子跃迁，从而帮助解释光吸收数据，已经使用时间依赖密度泛函理论 （TD-DFT） 水平进行了理论计算。这些计算提供了有关激发电子态性质的重要信息，这些电子态已被分配给价、混合价-里德伯格跃迁和里德伯格跃迁。由于缺乏有关 CDFA 离子状态的任何信息，我们还提供运动方程耦合簇单簇和双簇 （EOM-CCSD） 垂直电离能量。这两种化合物在地球大气中的光解寿命也是根据绝对光吸收横截面数据估计的。