The project focuses on stability of liquid metal films and other structures on nanoscale. Nanosecond pulsed laser melting can produce spatially correlated nanoparticle assemblies, and the main goal is to explore the fundamental mechanisms driving this process. The distinguishing feature of this project is synergetic approach including modeling based on continuum fluid mechanics, targeted experiments, and supporting molecular dynamics simulations. The central goal is to leverage careful and thorough experimental investigations and state of the art theoretical and computational modeling of nanoscale liquid metal films to address several basic scientific questions such as: How to develop reasonably simple but predictive models to describe the forces relevant to liquid metals on nanoscale? To which degree can multi-scale modeling (molecular dynamics and continuum fluid dynamics) approaches be used to bridge experimental length scales? How to use the interactions characterizing molten liquid metals to promote self-assembly and self-organization at the nanoscale?
To address these questions, the platinum-ruthenium binary metal system on graphite substrates will be investigated. The system was carefully chosen so complementary continuum fluid dynamics and molecular dynamics simulations can be performed to understand the relevant interface potentials as well as competing interfacial mixing and solidification dynamics. Thin films and other geometries will be synthesized to investigate solid-liquid-vapor interactions relevant to instabilities leading to nanoparticle assemblies, study the effects that the solidification dynamics has on synthesis of multi-functional nano particles, and to explore imposed thermal instabilities as a route to directed assembly. Experimental efforts will be complemented by theoretical and computational work, involving multi-dimensional nonlinear simulations including liquid-solid interaction potentials, thermal and phase change effects, and diffusive mixing, among other effects.
Successful completion of the project will allow for significant advancement in under- standing of fundamental liquid phase assembly of metallic nanostructures. One example of an application where self- and directed assembly of nano particles is of significant importance is the design of solar cell devices where it is known that the size and distribution of metallic particles is related to plasmon coupling to incident energy, with the huge potential in increasing the yield. More generally, nano-assembly is of importance in a variety of fields, ranging from energy related to DNA sequencing. The project also includes development of complementary continuous and molecular dynamics simulations which will allow for bridging of relevant spatial and temporal scales, providing general insight regarding limits and applicability of continuum modeling on nanoscale. The project will include graduate and undergraduate students from multiple STEM disciplines and will involve international collaboration with a research group in Argentina.
