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MSE Seminar - Prof. Stephen B. Cronin, University of Southern California
Friday, March 13, 2009
1:00 p.m.
Rm. 2108, Chemical and Nuclear Engineering Bldg.
For More Information:
Annette Mateus
301 405 5207
amateus@umd.edu

"One-Dimensional Physics in Individual Suspended Carbon Nanotubes"

Metallic single-walled carbon nanotubes (SWNTs) provide an excellent system for studying interesting one-dimensional physics, including exceptionally strong electron-phonon coupling, Kohn anomalies, ballistic electron transport, and strongly correlated electrons. In this presentation, I will report measurements of nearly defect free, suspended carbon nanotubes under high voltage biases. Raman spectroscopy reveals exceptionally strong electron-phonon coupling, arising from Kohn anomalies, which result in mode selective electron-phonon coupling, negative differential conductance (NDC), and non-equilibrium phonon populations. Due to the extremely long electron lifetimes, we observe a breakdown of the Born-Oppenheimer approximation, as deduced from the gate voltage induced changes in the vibrational energies of suspended carbon nanotubes.

Spatially-resolved temperature measurements of carbon nanotubes under high applied bias voltages reveal a unique thermal conduction mechanism that is quite different from bulk materials, and enables these nanotube devices to operate at extremely high power densities.

Lastly, I will report strikingly large variations in the Raman intensity of pristine metallic SWNTs in response to gate voltages, which are attributed to an insulating state of the strongly correlated electrons.

This Event is For: Public

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