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.
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, had studied the assembly of atoms and molecules into clusters at the ultralow temperatures achievable in superfluid droplets of helium. These studies were focused on such species as metal atoms and hydrocarbon molecules, among others. The experiments were carried out in the droplets themselves by employing laser methods in conjunction with mass spectroscopy. Some of the assembled clusters were also imaged by way of electron microscopy or x-ray diffraction. The studied clusters ranged 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 was to investigate the mechanisms of low temperature aggregation and to elucidate the structure and excitations in such clusters with size. The outcomes of this project include: - The development of new technique for measurements of the average sizes of helium droplets. - Observation of quantum vortices in helium droplets and their use for growth of metallic nano-wires. - Using single shot X-ray coherent diffraction imaging for attaining shapes and vorticity in superfluid He droplets, as well as of the structure of the clusters therein. - Observation of metal-molecule core-shell clusters in He droplets. The large helium droplets which were employed in this project may be useful vehicles for making new materials. The assembly and study of nanometer-sized clusters in droplets of helium not only extended the variety of the nanomaterials available to researchers today but also contributed towards the establishment of novel physical methods of low temperature fabrication. Students working with Prof. Vilesov have received extensive training in such cutting-edge technologies including, but not limited to, fast electronics, high vacuum methods, optical and x-ray laser methods, high resolution electron microscopy and x-ray diffraction microscopy.
