The research objective of this award is to correlate the local, atomic-scale structure of graphene nanoresonators with their non-local oscillatory response at high driving frequencies. This will be performed by combining high-resolution scanning tunneling microscopy with high frequency opto-electric actuation techniques to probe suspended graphene membranes. We will investigate clamped, suspended membranes having diameters down to 25 nm, a regime that has so far been inaccessible to dynamical measurement. Using a combination of ion irradiation, high energy electrons, and adsorbate deposition, we will control and characterize specific defect and adsorbate configurations of graphene nanoresonators and monitor how this affects their resonant and dissipative behavior. The nonlinear tunnel current of a scanning tunneling microscope will be used here in a new rectifying mode that will serve as a sensitive probe of high frequency surface oscillatory amplitude and spatial eigenmodes. This will provide a powerful new tool for testing multi-scale theoretical models that combine atomistically defined defect configurations with continuum material properties.
This research will explore new physical phenomena that have been predicted but never before observed, such as the effect of specific defect configurations on the dynamical susceptibility of strained, suspended graphene nanoresonators. The research will enable an entirely new technique of microscopy that marries atomic-scale spatial resolution with high-frequency dynamical characterization. This will facilitate the exploration of nanostructure processes and behavior that were previously inaccessible due to a lack of tools for simultaneously measuring the atomic scale properties and oscillatory response of individual clamped graphene nanoresonators. The potential impact on technology is strong, since this work should result in new types of nanoresonators that will be applicable in the areas of nano-electronics, communications, chemical detection, mass sensing, charge sensing, probing quantum fluctuations, and general exploration of elastic behavior at the atomic scale. The impact on education and outreach will also be strong. This project will provide scientific training to graduate students, undergraduates, and high school students in a strongly interdisciplinary area
