Engin Selma, González-Vázquez Jesús, Maliyar Gianluigi Grimaldi, Milosavljević Aleksandar R, Ono Taishi, Nandi Saikat, Iablonskyi Denys, Kooser Kuno, Bozek John D, Decleva Piero, Kukk Edwin, Ueda Kiyoshi, Martín Fernando
Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
Struct Dyn. 2019 Sep 11;6(5):054101. doi: 10.1063/1.5106431. eCollection 2019 Sep.
We have performed a full-dimensional theoretical study of vibrationally resolved photoelectron emission from the valence shell of the water molecule by using an extension of the static-exchange density functional theory that accounts for ionization as well as for vibrational motion in the symmetric stretching, antisymmetric stretching, and bending modes. At variance with previous studies performed in centrosymmetric molecules, where vibrationally resolved spectra are mostly dominated by the symmetric stretching mode, in the present case, all three modes contribute to the calculated spectra, including intermode couplings. We have found that diffraction of the ejected electron by the various atomic centers is barely visible in the ratios between vibrationally resolved photoelectron spectra corresponding to different vibrational states of the remaining HO cation (the so-called -ratios), in contrast to the prominent oscillations observed in K-shell ionization of centrosymmetric molecules, including those that only contain hydrogen atoms around the central atoms, e.g., CH. To validate the conclusions of our work, we have carried out synchrotron radiation experiments at the SOLEIL synchrotron and determined photoelectron spectra and -ratios for HO in a wide range of photon energies, from threshold up to 150 eV. The agreement with the theoretical predictions is good.
我们通过扩展静态交换密度泛函理论，对水分子价壳层的振动分辨光电子发射进行了全维度理论研究，该理论考虑了电离以及对称伸缩、反对称伸缩和弯曲模式下的振动运动。与之前在中心对称分子中进行的研究不同，在那些研究中，振动分辨光谱主要由对称伸缩模式主导，而在当前情况下，所有三种模式都对计算光谱有贡献，包括模式间的耦合。我们发现，与在中心对称分子的K壳层电离中观察到的显著振荡相反，在对应于剩余HO阳离子不同振动态的振动分辨光电子光谱之间的比率（所谓的 - 比率）中，由各个原子中心对出射电子的衍射几乎不可见，包括那些仅在中心原子周围含有氢原子的分子，例如CH。为了验证我们工作的结论，我们在SOLEIL同步加速器上进行了同步辐射实验，并在从阈值到150 eV的宽光子能量范围内测定了HO的光电子光谱和 - 比率。与理论预测的一致性良好。
