Matthew Gebbie

Title: Tuning Electrostatic Forces in Ionic Liquids and Mapping the Nucleation Landscape of Diamond

Molecular forces are fundamental to wide-ranging challenges, from increasing ion transport efficiency in electrolytes, to combating protein aggregation in neurodegenerative diseases. In this seminar, I will present two examples of systematically varying molecular forces to investigate foundational theories in complex interfaces. I will first discuss using nanoscale force measurements to determine the origin of energy storage in ionic liquid-electrode interfaces. Ionic liquids show promise as nontoxic electrolytes, but higher conductivities are needed for applications. While ionic liquids were initially hypothesized to have extremely high free ion densities, we discovered that greater than 99.99% of the ions in ionic liquids behave as neutral pairs. From these results, we propose a new way of envisioning concentrated electrolytes to guide the design of high performance ionic liquids and energy electrolytes.

I will then present an approach for directly measuring the sub-critical nucleation energy landscape of diamond, a previously inaccessible regime in a core physical process. Diamond exhibits potential for biological imaging and quantum sensing. However, inconsistencies surround prior models of diamond nucleation, hindering the synthesis of high quality diamond for molecular sensing. By measuring relative nucleation probabilities from atomically-defined diamond templates, diamondoids, we find that critical nuclei are 26 carbon atom clusters composed solely of surface atoms, with a nucleation barrier that is four orders of magnitude smaller than classical estimates. Our results answer key questions regarding diamond synthesis and support non-classical concepts for nucleation and growth through multi-step intermediates.

Bio:Matthew Gebbie received his Ph.D. in Materials from UC Santa Barbara in 2016, where he was a 2011-2015 Science and Engineering Fellow in the NSF Center for Nanotechnology in Society. With guidance from Prof. Jacob Israelachvili, Matthew led research that substantially progressed a molecular level, mechanistic understanding of how electrostatic correlations govern the properties of ionic liquids and underwater peptide-based adhesives. Currently, Matthew is a GLAM Postdoctoral Fellow at Stanford University, where he works with Prof. Nicholas Melosh to tackle fundamental problems in diamond nanomaterials to enable single molecule, fluorescence-based electromagnetic sensing and advanced biological imaging.