Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.
Int J Mol Sci. 2022 Mar 25;23(7):3613. doi: 10.3390/ijms23073613.
Properties of clusters often depend critically on the exact number of atomic or molecular building blocks, however, most methods of cluster formation lead to a broad, size distribution and cluster intensity anomalies that are often designated as magic numbers. Here we present a novel approach of breeding size-selected clusters via pickup of dopants into multiply charged helium nanodroplets. The size and charge state of the initially undoped droplets and the vapor pressure of the dopant in the pickup region, determines the size of the dopant cluster ions that are extracted from the host droplets, via evaporation of the helium matrix in a collision cell filled with room temperature helium or via surface collisions. Size distributions of the selected dopant cluster ions are determined utilizing a high-resolution time of flight mass spectrometer. The comparison of the experimental data, with simulations taking into consideration the pickup probability into a shrinking He droplet due to evaporation during the pickup process, provides a simple explanation for the emergence of size distributions that are narrower than Poisson.
团簇的性质通常取决于原子或分子构建块的确切数量，然而，大多数团簇形成方法会导致广泛的、尺寸分布的和团簇强度异常，这些异常通常被指定为“幻数”。在这里，我们提出了一种通过将掺杂剂吸入多电荷氦纳米液滴中培育尺寸选择的团簇的新方法。最初未掺杂的液滴的尺寸和电荷状态以及在拾取区域中掺杂剂的蒸气压，决定了通过在充满室温氦气的碰撞室中蒸发氦基质或通过表面碰撞从主体液滴中提取的掺杂剂团簇离子的尺寸。利用高分辨率飞行时间质谱仪确定所选掺杂剂团簇离子的尺寸分布。将实验数据与考虑到由于拾取过程中的蒸发而在缩小的 He 液滴中发生的拾取概率的模拟进行比较，为出现比泊松分布更窄的尺寸分布提供了一个简单的解释。
