Adventurous Research in Chemistry / Synthesis and Characterisation of Novel Nanomaterials

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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.