Mozhayskiy Vadim, Slipchenko Mikhail N, Adamchuk Vera K, Vilesov Andrey F
Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA.
J Chem Phys. 2007 Sep 7;127(9):094701. doi: 10.1063/1.2759927.
The utility of continuous beam of helium droplets for assembly, transport, and surface deposition of metal and molecular clusters is studied. Clusters of propyne having from about 10 to 10(4) molecules were obtained via sequential pickup of molecules by He droplets with average sizes in the range of 10(4)-10(7) atoms. The maximum attainable flux of the propyne molecules carried by He droplets was found to be in the range of (5-15)x10(15) molecules sr(-1) s(-1), being larger in larger droplets. The size of the clusters and the flux of the transported species are ultimately limited by the evaporative extinction of the entire helium droplet upon capture of particles. It is shown that the attenuation of the He droplet beam in the process of the cluster growth can be used in order to obtain the average size and the binding energy of the clusters. Furthermore, we used He droplets for assembling and surface deposition of gold and silver clusters having about 500 atoms. Typical deposition rate of metal atoms of about 3 x 10(15) atoms sr(-1) s(-1) is comparable to or larger than obtained with other beam deposition techniques. We propose that doping of He droplets by Au and Ag atoms in two separate pickup chambers leads to formation of the bimetal clusters having core-shell structure.
研究了连续氦滴束在金属和分子团簇的组装、传输及表面沉积方面的应用。通过尺寸平均在10⁴ - 10⁷ 个原子范围内的氦滴依次捕获分子，得到了含有约10到10⁴ 个分子的丙炔团簇。发现氦滴携带的丙炔分子的最大可达到通量在(5 - 15)×10¹⁵ 分子 sr⁻¹ s⁻¹ 范围内，且液滴越大通量越大。团簇的尺寸和传输物种的通量最终受捕获粒子时整个氦滴蒸发消失的限制。结果表明，在团簇生长过程中氦滴束的衰减可用于获取团簇的平均尺寸和结合能。此外，我们用氦滴对含有约500个原子的金和银团簇进行组装和表面沉积。约3×10¹⁵ 原子 sr⁻¹ s⁻¹ 的典型金属原子沉积速率与其他束流沉积技术相当或更高。我们提出，在两个独立的捕获腔室中用金和银原子对氦滴进行掺杂会导致形成具有核壳结构的双金属团簇。
