Condensed Matter Physics Seminar

2 p.m., Thursday, October 13, 2005
Room 1201, Physics Building

 Seeing Nanosystems

John Cumings

(University of Maryland)

Abstract:  With the relevant length scales of both electrical and mechanical devices reaching into the nanometer-domain, transmission electron microscopy is poised to emerge as a powerful tool for studying the dynamic properties of these new functional devices. At these length scales, it is difficult to uncover basic behavior, and the ability to simply observe systems under dynamic conditions allows a variety of microscopic phenomena to be understood. Electron microscopy opens these doors but also allows the analysis of subtle dynamic effects, such as structural changes, mass transport, electromagnetic fields, and heat flow. I will outline the general techniques and capabilities of this sort of in-situ microscopy.

Specifically, I will present work on studying the mechanical and electrical properties of carbon nanotube devices. Multiwall carbon nanotubes are concentrically stacked tubular sheets of graphite, where the spacing between each cylinder is simply the natural spacing of graphite. Using a custom-built in-situ nanomanipulation probe, I have shown that it is possible to slide nanotube layers in a telescopic extension mode that exhibits low friction, demonstrating the potential of nanotubes as the ultimate synthetic nanobearing. During this telescopic extension, the electrical resistance of the nanotube devices increases, opening the possibility that these devices can also be used as nanoscale rheostats. I will also present work on using electron holography inside an electron microscope to study the electric field distribution in nanotube field-emission devices. These measurements together demonstrate the wealth of information that can be obtained and frontiers that can be opened by putting operational nanodevices inside an electron microscope.

Host:  Fuhrer
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