Desrier Antoine, Romanzin Claire, Lamarre Nicolas, Alcaraz Christian, Gans Bérenger, Gauyacq Dolores, Liévin Jacques, Boyé-Péronne Séverine
Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS UMR 8214, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France.
Laboratoire de Chimie Physique, CNRS UMR 8000, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay Cédex, France.
J Chem Phys. 2016 Dec 21;145(23):234310. doi: 10.1063/1.4972019.
Threshold-photoionization spectroscopy of cyanoacetylene (HCN) and its N isotopologue has been investigated in the vacuum-ultraviolet range with a synchrotron-based experiment allowing to record threshold-photoelectron spectrum and photoion yield over a large energy range (from 88 500 to 177 500 cm, i.e., from 11 to 22 eV). Adiabatic ionization energies towards the three lowest electronic states XΠ, A Σ+2, and B Π2 are derived from the threshold-photoelectron spectrum. A detailed description of the vibrational structure of these states is proposed leading to the determination of the vibrational frequencies for most modes. The vibrational assignments and the discussion about the electronic structure are supported by multireference ab initio calculations (CASPT2, MRCI). Unprecedented structures are resolved and tentatively assigned in the region of the B← X transition. Exploratory calculations highlight the complexity of the electronic landscape of the cation up to approximately 10 eV above its ground state.
利用基于同步加速器的实验，在真空紫外波段对氰乙炔（HCN）及其氮同位素进行了阈值光电离光谱研究，该实验能够在较大能量范围（从88500至177500厘米⁻¹，即从11至22电子伏特）记录阈值光电子能谱和光离子产率。从阈值光电子能谱中得出了向三个最低电子态XΠ、A Σ⁺₂和B Π₂的绝热电离能。对这些态的振动结构进行了详细描述，从而确定了大多数模式的振动频率。振动归属以及关于电子结构的讨论得到了多参考从头算计算（CASPT2、MRCI）的支持。在B←X跃迁区域分辨出了前所未有的结构，并进行了初步归属。探索性计算突出了阳离子在其基态上方约10电子伏特范围内电子态势的复杂性。
