Gerlach Marius, Fantuzzi Felipe, Wohlfart Lilith, Kopp Karina, Engels Bernd, Bozek John, Nicolas Christophe, Mayer Dennis, Gühr Markus, Holzmeier Fabian, Fischer Ingo
Institute of Physical and Theoretical Chemistry, University of Würzburg, 97074 Würzburg, Germany.
Synchrotron SOLEIL, 91192 Gif-sur-Yvette, France.
J Chem Phys. 2021 Mar 21;154(11):114302. doi: 10.1063/5.0044506.
We report a study on the fragmentation of core-ionized and core-excited isocyanic acid, HNCO, using Auger-electron/photoion coincidence spectroscopy. Site-selectivity is observed both for normal and resonant Auger electron decay. Oxygen 1s ionization leads to the CO + NH ion pairs, while nitrogen 1s ionization results in three-body dissociation and an efficient fragmentation of the H-N bond in the dication. Upon 1s → 10a' resonant excitation, clear differences between O and N sites are discernible as well. In both cases, the correlation between the dissociation channel and the binding energy of the normal Auger electrons indicates that the fragmentation pattern is governed by the excess energy available in the final ionic state. High-level multireference calculations suggest pathways to the formation of the fragment ions NO and HCO, which are observed although the parent compound contains neither N-O nor H-C bonds. This work contributes to the goal to achieve and understand site-selective fragmentation upon ionization and excitation of molecules with soft x-ray radiation.
我们报道了一项利用俄歇电子/光离子符合光谱对核心电离和核心激发的异氰酸（HNCO）进行碎片化研究。在正常和共振俄歇电子衰变中均观察到了位点选择性。氧1s电离产生CO + NH离子对，而氮1s电离导致三体解离以及双离子中H-N键的有效断裂。在1s → 10a'共振激发时，O和N位点之间也存在明显差异。在这两种情况下，解离通道与正常俄歇电子结合能之间的相关性表明，碎片化模式由最终离子态中可用的过剩能量决定。高水平多参考计算表明了形成碎片离子NO和HCO的途径，尽管母体化合物既不包含N-O键也不包含H-C键，但仍观察到了这些碎片离子。这项工作有助于实现并理解利用软X射线辐射对分子进行电离和激发时的位点选择性碎片化这一目标。
