Adventurous Research in Chemistry / Synthesis and Characterisation of Novel Nanomaterials

目的是探索一种全新的途径来生产独特种类的纳米颗粒。这一假设源于化学系正在进行的实验，通过将分子包裹在超流体液氦纳米液滴（LHNDs）中，研究分子之间的弱相互作用。这些液滴的特点是超低的平衡温度（0.38 K），但它们的超流动性意味着在气相中遇到液滴的物质会粘附在液滴表面，然后向液滴中心移动，并在快速（<1毫秒）的时间尺度内凝固。虽然目前是化学物理学家的工具，但该技术在化学和材料科学方面具有应用潜力。在气相中顺序或同时添加掺杂剂将允许合成由核心和几乎无限选择的层组成的独特纳米级物体。此外，周围的液氦对于这些纳米颗粒完整地软着陆是理想的，因为弱束缚的氦原子会在撞击时蒸发损失几乎所有的碰撞能量。多层纳米颗粒的生长将通过不同类型的氦纳米液滴来探索，从相对较小的（数万个氦原子）到非常大的（b>108个氦原子）。长期目标是证明，通过针孔喷嘴将液氦膨胀到真空室中，可以培养出稳定的单分散氦滴。这种独特的来源应该提供一种新型的超低温反应器，用于生长大型的，在某种程度上，尺寸选择的纳米颗粒，并将这些物种沉积在固体目标上。将采用高分辨率显微镜来描述形成的物种。奇异的和全新的纳米颗粒，如流体核（气体或液体）封装在固体壳内的纳米颗粒，可能通过这种途径生产出来，这种生长过程的可行性将成为计划项目的一部分。

The aim is to explore an entirely novel route for producing unique varieties of nanoparticles. The premise stems from experiments already underway in the Chemistry Department in which weak interactions between molecules are being explored by encasing them in superfluid liquid helium nanodroplets (LHNDs). These droplets are characterised by an ultra-low equilibrium temperature (0.38 K) but their superfludity means that species encountering the droplets in the gas phase will stick to the droplet surface, will then move towards the centre of the droplet, and will coagulate, all within a rapid (<1 ms) timescale. Although currently the tool of chemical physicists, this technology has the potential for applications in chemistry and materials science. The sequential or simultaneous addition of dopants in the gas phase will allow the synthesis of unique nanoscale objects composed of cores and layers of almost infinite choice. Furthermore, the surrounding liquid helium is ideal for soft-landing these nanoparticles intact on substrates, since the weakly bound helium atoms will dissipate virtually all of the collision energy by evaporative loss on impact.The growth of multi-layer nanoparticles will be explored using various types of helium nanodroplets, ranging from relatively small ones (tens of thousands of helium atoms) through to extremely large ones (>>108 atoms). The long-term aim is to show that a stable source of monodisperse helium droplets can be grown by expanding liquid helium through a pinhole nozzle into a vacuum chamber. This unique source should provide a new type of ultra-low temperature reactor for growing large and, to some extent, size-selected nanoparticles and depositing these species on solid targets. High resolution microscopy will be employed to characterise the species formed. Exotic and entirely novel nanoparticles, such as ones with fluid cores (gas or liquid) encapsulated within solid shells, can potentially be produced by this route and the feasibility of this growth process will form part of the planned project.