Correlating Local Defect Structure with Dynamical Response in Graphene

该奖项的研究目标是将石墨烯纳米谐振器的局域原子尺度结构与其在高驱动频率下的非局域振荡响应相关联。这将通过结合高分辨率扫描隧道显微镜和高频光电驱动技术来探测悬浮的石墨烯薄膜来实现。我们将研究直径低至25纳米的固定式悬浮膜，这一区域到目前为止还无法进行动态测量。利用离子辐照、高能电子和吸附沉积的组合，我们将控制和表征石墨烯纳米谐振器的特定缺陷和吸附配置，并监测这如何影响它们的共振和耗散行为。扫描隧道显微镜的非线性隧道电流将被用在一种新的整流模式中，作为高频表面振荡幅度和空间本征模的灵敏探针。这将为测试原子定义的缺陷组态与连续介质材料性质相结合的多尺度理论模型提供一个强大的新工具。这项研究将探索已经预测但从未观察到的新物理现象，例如特定的缺陷组态对应变悬浮石墨烯纳米谐振器动态磁化率的影响。这项研究将使一种全新的显微技术成为可能，这种技术将原子尺度的空间分辨率与高频动态表征结合在一起。这将促进对纳米结构过程和行为的探索，这些过程和行为以前由于缺乏同时测量单个固定的石墨烯纳米谐振器的原子尺度属性和振荡响应的工具而无法获得。这对技术的潜在影响是巨大的，因为这项工作应该会产生新型的纳米谐振器，这些谐振器将应用于纳米电子、通信、化学检测、质量传感、电荷传感、探测量子涨落，以及在原子尺度上对弹性行为的一般探索。对教育和外展的影响也将是巨大的。该项目将为研究生、本科生和高中生在一个跨学科的领域提供科学培训。

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