Pysanenko Andriy, Bergmeister Stefan, Scheier Paul, Fárník Michal
J. Heyrovský Institute of Physical Chemistry, v.v.i., The Czech Academy of Sciences, Dolejškova 2155/3, 182 23, Prague, Czech Republic.
Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
Phys Chem Chem Phys. 2022 Nov 18;24(44):27128-27135. doi: 10.1039/d2cp02979k.
We investigate electron attachment to large ammonia clusters doped with a single benzene (Bz) molecule (NH)·Bz, ≈ 320. Negatively charged clusters are probed by mass spectrometry, and the energy-dependent ion yields are derived from mass spectra measured at different electron energies. The ion efficiency curves of pure ammonia clusters exhibit two maxima. At around 6 eV, (NH)NH ions are produced dissociative electron attachment (DEA) to NH molecules. (NH) ions produced at this energy are formed by DEA followed by fragment caging. At low energies around 1.3 eV, only (NH) ions are formed for cluster sizes ≥ 35 that correspond to solvated electrons in ammonia clusters. The doped (NH)·Bz cluster ions exhibit essentially the same energy dependence. The (NH)·Bz ions are metastable and evaporate NH molecule(s), while pure (NH) ions are stable. The lifetime for NH molecule evaporation from the Bz-doped clusters was estimated as ≈ 18 μs. We interpret the metastability of the doped clusters by the charge localization on a Bz ion solvated in the ammonia, which is accompanied by an energy release leading to the evaporation of NH molecule(s).
我们研究了单个苯（Bz）分子掺杂的大型氨簇（NH）·Bz（≈320）上的电子附着情况。通过质谱法探测带负电的簇，并从在不同电子能量下测量的质谱中得出能量相关的离子产率。纯氨簇的离子效率曲线呈现出两个最大值。在约6电子伏特时，通过对NH分子的解离电子附着（DEA）产生（NH）NH离子。在此能量下产生的（NH）离子是由DEA随后的碎片笼闭形成的。在约1.3电子伏特的低能量下，对于尺寸≥35的簇，仅形成（NH）离子，这对应于氨簇中的溶剂化电子。掺杂的（NH）·Bz簇离子表现出基本相同的能量依赖性。（NH）·Bz离子是亚稳的，会蒸发NH分子，而纯（NH）离子是稳定的。从掺杂Bz的簇中蒸发NH分子的寿命估计约为18微秒。我们通过氨中溶剂化的Bz离子上的电荷定位来解释掺杂簇的亚稳性，这伴随着能量释放导致NH分子的蒸发。
