LERMA UMR CNRS 8112, Observatoire de Paris-Meudon, 5 place Jules-Jansen, 92195 Meudon, France.
J Chem Phys. 2013 Nov 14;139(18):184304. doi: 10.1063/1.4826467.
Photoionization of dicyanoacetylene was studied using synchrotron radiation over the excitation range 8-25 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and detailed spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of dicyanoacetylene was measured as 11.80 ± 0.01 eV. A detailed analysis of the cation spectroscopy involves new aspects and new assignments of the vibrational components to excitation of the quasi-degenerate A(2)Πg, B(2)Σg(+) states as well as the C(2)Σu(+) and D(2)Πu states of the cation. Some of the structured autoionization features observed in the 12.4-15 eV region of the total ion yield spectrum were assigned to vibrational components of valence shell transitions and to two previously unknown Rydberg series converging to the D(2)Πu state of C4N2(+). The appearance energies of the fragment ions C4N(+), C3N(+), C4(+), C2N(+), and C2(+) were measured and their heats of formation were determined and compared with existing literature values. Thermochemical calculations of the appearance potentials of these and other weaker ions were used to infer aspects of dissociative ionization pathways.
使用同步辐射，在 8-25 eV 的激发范围内，通过光电离-光电离符合技术，研究了二氰基乙炔的光致电离。记录了母体离子的绝对电离截面和详细的光谱特征。二氰基乙炔的绝热电离能测量值为 11.80 ± 0.01 eV。对阳离子光谱的详细分析涉及到准简并 A(2)Πg、B(2)Σg(+)态以及阳离子的 C(2)Σu(+)和 D(2)Πu 态激发的振动分量的新方面和新分配。在总离子产率谱的 12.4-15 eV 区域观察到的一些结构化自电离特征被分配给价壳层跃迁的振动分量以及两个以前未知的向 C4N2(+)的 D(2)Πu 态收敛的里德堡系列。碎片离子 C4N(+)、C3N(+)、C4(+)、C2N(+)和 C2(+)的出现能被测量，它们的生成热被确定，并与现有文献值进行比较。这些和其他较弱离子的出现势的热化学计算被用于推断离解电离途径的各个方面。
