Seminars Archive

X-ray Imaging of Nanostructures in Superfluid Helium Droplets

Dr. Rico Mayro Tanyag
Aarhus University, Denmark

Abstract
A self-bound superfluid helium droplet is an extremely cold and frictionless medium for growing metastable and self-organized dopant nanostructures. Their visualization offers an opportunity to identify different structure formation regimes and unravel the mechanisms driving their assembly. Using x-ray coherent diffractive imaging, three regimes have been distinguished: vortex-free aggregation, vortex-induced aggregation, and cluster network formation. In this talk, we point out that the regime boundaries depend on the droplet size and the number of dopants, and on how the droplet's rotational state influences the types of structure formed. Additionally, the transition between the vortex-free and vortex-induced aggregation was discovered to occur when the droplet contains about 108 atoms; only partially affected by how the droplets are generated. These results not only present a means of controlling structure formation in superfluid helium droplets, but they also lay the foundation for imaging the assembly of nanostructures with different intermolecular forces for future studies.