ENME Webcast Fall 2006

Leaders in Mechanical Engineering Lecture Series

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Title: Multi-Scale Modeling Of Carbon Nanotube Atomic Force Microscopy Imaging: What You See Is Not Always What You Get
Professor Santiago Solares
University of Maryland, Department of Mechanical Engineering

Original Air Date: Friday, November 3rd at 2:00pm

Abstract: Atomic-resolution microscopy techniques have developed rapidly in the last few decades and have also been proposed as precursors of bottom-up nanofabrication tools. Among these techniques, Atomic Force Microscopy (AFM) offers the widest range of controllable mechanical motion and is of significant interest in the development of nanomechanical tools. Carbon nanotubes (CNTs) are some of the most interesting AFM probes due to their unique geometry, robustness, unusual mechanical and electrical properties, and ease of chemical functionalization, and have promised important enhancements to the imaging process. Despite this progress there are still concerns about the fidelity of the AFM images obtained with CNTs, and it is not clear to what extent the finest probes provide better imaging resolution or result in a loss of structural information. This question has been complicated by the lack of modeling tools that combine the various relevant length scales of the process, which range from an atomistic treatment at the CNT tip to a classical treatment of the AFM cantilever, whose dimensions are several orders of magnitude larger. We have developed a theoretical methodology that combines molecular dynamics and AFM dynamics in the simulation of AFM imaging with CNTs or conventional silicon tips. So far, this methodology has been applied to explain the abnormally low CNT probe resolutions observed during recent imaging experiments, and to demonstrate the existence of up to an infinite number of mathematical imaging solutions when using CNT probes (previously only two solutions were known). Next steps include the development of low-impact probes to be used on sensitive samples and the design of AFM-inspired manipulation tools.