Assembly and spectroscopic interrogation of large atomic and molecular clusters in helium droplets

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Through this award, funded by the Chemical Structure, Dynamics, and Mechanisms Program of the Division of Chemistry, Prof. Andrey Vilesov from the University of Southern California, along with his graduate student researchers, will study the assembly of atoms and molecules into clusters at the ultralow temperatures achievable in superfluid droplets of helium. These studies will focus on such species as metal atoms and hydrocarbon molecules, among others. The experiments will be carried out in the droplets themselves by employing laser methods in conjunction with mass spectroscopy. Many of the assembled clusters will also be imaged by way of electron microscopy. The clusters to be studied will range in size from just a few atoms/molecules to tens of millions and vary in composition from single-species clusters to mixed, core-shell metal-molecule clusters. The goal of these studies is to investigate the mechanisms of low temperature aggregation and to elucidate the structure and excitations in such clusters with size. The large helium droplets that Prof. Vilesov proposes to use may be useful vehicles for making new and interesting materials. The assembly and study of nanometer-sized clusters in droplets of helium will not only extend the variety of the nanomaterials available to researchers today but will also contribute toward the establishment of novel physical methods of low temperature fabrication. Students working with Prof. Vilesov have and will continue to receive extensive training in such cutting-edge technologies including, but not limited to, fast electronics, high vacuum methods, laser methods, and high resolution microscopy. Prof. Vilesov has a strong history of international collaboration and this will likely continue through this work.