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Record-setting innovation in optical microscopy. (Microscopy).

As nanoscale objects become smaller and more prevalent, the need for enhanced imaging and resolution techniques grows. A team of scientists at the Univ. of Rochester, N.Y., led by Lukas Novotny and Achim Hartschuh and in collaboration with researchers at Harvard Univ., Cambridge, Mass., and Portland State Univ., Ore., have taken on that challenge to produce the highest resolution optical image to date.

Their study was conducted on carbon nanotubes and used near-field Raman microscopy, to produce detailed images with a resolution of 25 nm. "There are other methods that can see smaller structures, but none use light, which is rich in information," says Novotny. Based on the light scattering properties of the Raman Effect, the team used a laser to illuminate the side of a silver-tipped wire measuring about 10 nm across. They then scanned the tip over a sample surface. This excited electrons in the silver tip and the atoms in the sample created packets of light that were collected and processed.

"With this technique, we obtain a detailed spectrum for every point on a surface," says Novotny. This technique, known as "near-field" surface-enhanced Raman spectroscopy, can intensify the generally low signal strengths of Raman signals by factors of up to [10.sup.15]. Such an increase in signal intensity allows scientists to study single molecules and provides enhanced structural information about a sample's molecular composition. The team hopes that this method can also be applied to minute structures, such as proteins.

Institute of Optics, Univ. of Rochester, N.Y.
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Publication:R & D
Article Type:Brief Article
Geographic Code:1U2NY
Date:Apr 1, 2003
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