Falconer Travis M, Lewis William K, Bemish Raymond J, Miller Roger E, Glish Gary L
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
Rev Sci Instrum. 2010 May;81(5):054101. doi: 10.1063/1.3386584.
A strategy for forming and detecting cold ion-neutral clusters using superfluid helium nanodroplets is described. Sodium cations generated via thermionic emission are directed toward a beam of helium droplets that can also pick up neutral molecules and form a cluster with the captured Na(+). The composition of the clusters is determined by mass spectrometric analysis following a desolvation step. It is shown that the polar molecules H(2)O and HCN are picked up and form ion-neutral clusters with sizes and relative abundances that are in good agreement with those predicted by the statistics used to describe neutral cluster formation in helium droplets. Na(H(2)O)(n) clusters containing six to 43 water molecules were observed, a size range of sodiated water clusters difficult to access in the gas phase. Clusters containing N(2) were in lower abundance than expected, suggesting that the desolvation process heats the clusters sufficiently to dissociate those containing nonpolar molecules.
描述了一种使用超流氦纳米滴形成和检测冷离子-中性簇的策略。通过热电子发射产生的钠离子被导向一束氦滴，氦滴也可以捕获中性分子并与捕获的Na(+)形成簇。在去溶剂化步骤之后，通过质谱分析确定簇的组成。结果表明，极性分子H(2)O和HCN被捕获并形成离子-中性簇，其大小和相对丰度与用于描述氦滴中中性簇形成的统计预测结果高度一致。观察到含有6至43个水分子的Na(H(2)O)(n)簇，这是气相中难以获得的钠化水簇的尺寸范围。含有N(2)的簇的丰度低于预期，这表明去溶剂化过程使簇充分加热，从而使含有非极性分子的簇解离。
