Michiels Rupert, LaForge Aaron C, Bohlen Matthias, Callegari Carlo, Clark Andrew, von Conta Aaron, Coreno Marcello, Di Fraia Michele, Drabbels Marcel, Finetti Paola, Huppert Martin, Oliver Veronica, Plekan Oksana, Prince Kevin C, Stranges Stefano, Svoboda Vít, Wörner Hans Jakob, Stienkemeier Frank
Institute of Physics, University of Freiburg, 79104 Freiburg, Germany.
Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA.
Phys Chem Chem Phys. 2020 Apr 15;22(15):7828-7834. doi: 10.1039/d0cp00669f.
High intensity XUV radiation from a free-electron laser (FEL) was used to create a nanoplasma inside ammonia clusters with the intent of studying the resulting electron-ion interactions and their interplay with plasma evolution. In a plasma-like state, electrons with kinetic energy lower than the local collective Coulomb potential of the positive ionic core are trapped in the cluster and take part in secondary processes (e.g. electron-impact excitation/ionization and electron-ion recombination) which lead to subsequent excited and neutral molecular fragmentation. Using a time-delayed UV laser, the dynamics of the excited atomic and molecular states are probed from -0.1 ps to 18 ps. We identify three different phases of molecular fragmentation that are clearly distinguished by the effect of the probe laser on the ionic and electronic yield. We propose a simple model to rationalize our data and further identify two separate channels leading to the formation of excited hydrogen.
利用自由电子激光（FEL）产生的高强度极紫外（XUV）辐射在氨团簇内部产生纳米等离子体，目的是研究由此产生的电子-离子相互作用及其与等离子体演化的相互作用。在类似等离子体的状态下，动能低于正离子核心局部集体库仑势的电子被困在团簇中，并参与导致后续激发和中性分子碎片化的次级过程（例如电子碰撞激发/电离和电子-离子复合）。使用延时紫外激光，在-0.1皮秒至18皮秒的时间范围内探测激发的原子和分子态的动力学。我们识别出分子碎片化的三个不同阶段，这些阶段通过探测激光对离子产率和电子产率的影响而明显区分。我们提出一个简单模型来合理解释我们的数据，并进一步识别出导致激发态氢形成的两个独立通道。
