Ngai Aaron, Hartweg Sebastian, Asmussen Jakob D, Bastian Björn, Bonanomi Matteo, Callegari Carlo, Danailov Miltcho, di Fraia Michele, Feifel Raimund, Ganeshamandiram Sarang Dev, Krishnan Sivarama, LaForge Aaron, Landmesser Friedemann, Ltaief Ltaief Ben, Michelbach Moritz, Pal Nitish, Plekan Oksana, Rendler Nicolas, Raimondi Lorenzo, Richter Fabian, Scognamiglio Audrey, Sixt Tobias, Squibb Richard J, Dulitz Katrin, Stienkemeier Frank, Mudrich Marcel
Institute of Physics, University of Freiburg, Freiburg, Germany.
Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
Sci Rep. 2025 Jan 25;15(1):3201. doi: 10.1038/s41598-024-84531-9.
Roaming reactions involving a neutral fragment of a molecule that transiently wanders around another fragment before forming a new bond are intriguing and peculiar pathways for molecular rearrangement. Such reactions can occur for example upon double ionization of small organic molecules, and have recently sparked much scientific interest. We have studied the dynamics of the [Formula: see text]-roaming reaction leading to the formation of [Formula: see text] after two-photon double ionization of ethanol and 2-aminoethanol, using an XUV-UV pump-probe scheme. For ethanol, we find dynamics similar to previous studies employing different pump-probe schemes, indicating the independence of the observed dynamics from the method of ionization and the photon energy of the disruptive probe pulse. Surprisingly, we do not observe a kinetic isotope effect in ethanol-[Formula: see text], in contrast to previous experiments on methanol where such an effect was observed. This distinction indicates fundamental differences in the energetics of the reaction pathways as compared to the methanol molecule. The larger number of possible roaming pathways compared to methanol complicates the analysis considerably. In contrast to previous studies, we additionally analyze a broad range of dissociative ionization products, which feature distinct dynamics from that of [Formula: see text] and allow initial insight into the action of the disruptive UV-probe pulse.
涉及分子中性片段的漫游反应是一种有趣且独特的分子重排途径，该中性片段在形成新键之前会短暂地围绕另一个片段游走。例如，这种反应可在小分子有机化合物的双电离过程中发生，最近引发了众多科学关注。我们利用XUV - UV泵浦 - 探测方案，研究了乙醇和2 - 氨基乙醇在双光子双电离后导致生成[化学式：见原文]的[化学式：见原文]漫游反应动力学。对于乙醇，我们发现其动力学与先前采用不同泵浦 - 探测方案的研究结果相似，这表明所观察到的动力学与电离方法以及破坏性探测脉冲的光子能量无关。令人惊讶的是，与先前在甲醇上观察到动力学同位素效应的实验不同，我们在乙醇 - [化学式：见原文]中未观察到这种效应。这种差异表明，与甲醇分子相比，反应途径的能量学存在根本差异。与甲醇相比，更多可能的漫游途径使得分析工作相当复杂。与先前的研究不同，我们还分析了广泛的解离电离产物，这些产物具有与[化学式：见原文]不同的动力学特征，并能让我们初步了解破坏性紫外探测脉冲的作用。
