[MOS] TODAY October 20, 2009

[Zina Queen]

Seminar on

Modern Optics and Spectroscopy

Advanced Rayleigh imaging for accurate carbon nanostructures

Jiwoong Park, Cornell University

Tuesday, October 20, 2009


12:00 - 1:00 p.m.






Carbon based nanostructures, including carbon nanotubes, graphenes, 
and graphene nanoribbons, have played a central role in nanoscale 
science and technology in the past decade. Even though many promising 
devices have been demonstrated using these individual carbon 
nanostructures-most notably with carbon nanotubes, applying them for 
larger scale devices has been difficult due to the enormous 
challenges that are unique to nanostructures. As the most notable 
example, there are no simple characterization methods for identifying 
the chirality indices of individual carbon nanotubes with a high 
throughput.  My group recently developed a powerful characterization 
method that allows spectrally resolved Rayleigh imaging of a large 
array of individual carbon nanotubes (CNTs) on a substrate. We 
successfully took a color scattering image of individual CNTs using a 
combination of carefully controlled laser illumination and refractive 
index matching. The unique color of each CNT reflects its electronic 
structure including the energies of van Hove singularities. Using 
this technique, we also studied electronic interactions between 
closely located parallel CNTs, which revealed a strong dipole 
coupling and enhancement/disappearance of Rayleigh signal. Our 
advanced Rayleigh imaging is much faster and more versatile than any 
other optical (Raman or PL) or scanned probe techniques (STM, AFM) 
that are currently used for nanotube characterization and will be a 
general tool for studying scattering spectra of other nanoscale 
objects.


Grier Room, MIT Bldg 34-401
Refreshments served after the lecture
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