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1.
Science ; 357(6349): 397-400, 2017 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-28751608

RESUMO

We used scanning tunneling microscopy to study low-angle grain boundaries at the surface of nearly planar copper nanocrystalline (111) films. The presence of grain boundaries and their emergence at the film surface create valleys composed of dissociated edge dislocations and ridges where partial dislocations have recombined. Geometric analysis and simulations indicated that valleys and ridges were created by an out-of-plane grain rotation driven by reduction of grain boundary energy. These results suggest that in general, it is impossible to form flat two-dimensional nanocrystalline films of copper and other metals exhibiting small stacking fault energies and/or large elastic anisotropy, which induce a large anisotropy in the dislocation-line energy.

2.
J Am Chem Soc ; 131(9): 3128-9, 2009 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-19222157

RESUMO

We directly compared ensemble spectroscopic measurements to a statistically rigorous single molecule electrical characterization of individual SWNT devices using a high throughput electrical probe station and reported, for the first time, a highly accurate extinction coefficient ratio for metallic to semiconducting SWNTs of 0.352 +/- 0.009. The systematic counting of metallic and semiconducting types from solution also allows us to examine the variances associated with device properties and therefore provide the first measure of potential defect generation during processing methods.


Assuntos
Elétrons , Nanotubos de Carbono/química , Análise Espectral Raman
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