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Zettl Research Group |
Research Project |
We have been developing techniques to manipulate nanotubes and perform electrical transport experiments while imaging inside a transmission electron microscope (TEM). For this purpose, we have designed and built a manipulator attached to a standard TEM sample stage. The manipulator is capable of moving samples around with nanometer resolution, similar to a scanning tunneling microscope (STM; see our other project page).
A TEM is an electron microscope that works very similar, in principle, to a standard light microscope, like you would find in a biology lab, with the exception that the illumination source is an electron beam. We use the TEMs at the National Center for Electron Microscopy, a public user facility located at Lawrence Berkeley National Lab (you can find more about them here). The great thing about TEM is that it is capable of acquiring images at high rates (video rates are standard), so that you can see what's going on, exactly as you do it. To get an image with a standard STM, you have to scan the tip across the surface back and forth many times, and the process of acquiring a single image can take several minutes.
Using the manipulator, we can make contact to a single nanotube, and bend it to observe the mechanical properties. Additionally, we also have the capability to measure electrical properties of the nanotubes. We can change the voltage applied across the nanotube, and measure the electrical current that flows as a result. Using this, we can correlate the electrical properties with the mechanical properties that we observe using the TEM.
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