Public Release:  Tiny rulers to measure nanoscale structures

American Institute of Physics

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IMAGE: In contrast to a conventional nanoparticle dimer plasmon ruler, this new one shows an approximately linear relationship between the resonance wavelength shifts and nanosphere dimer interparticle separation for a linear... view more

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College Park, MD (August 31, 2010) -- With the advent of nanometer-sized machines, there is considerable demand for stable, precise tools to measure absolute distances and distance changes. One way to do this is with a plasmon ruler. In physics jargon, a "plasmon" is the quasiparticle resulting from the quantization of plasma oscillation; it's essentially the collective oscillations of the free electron gas at a metallic surface, often at optical frequencies.

A noble metallic dimer (a molecule that results from combining two entities of the same species) has been used as a plasmon ruler to make absolute distance and distance change measurements.

Physicists at China's Wuhan University discovered that nanospheres combined with a nanorod dimer could be used to solve the problem of measurement sensitivity. They provide details about their findings in the American Institute of Physics' Journal of Applied Physics.

Shao-Ding Liu and Mu-Tian Cheng used a nanostructure as a linear plasmon ruler. Nanospheres were used to modify surface plasmon coupling of a nanorod dimer. They found that the resonance wavelength shift increases approximately linearly with the increasing of a nanosphere's interparticle separations -- resulting in a structure that's useful as a plasmon ruler with homogenous measurement sensitivity.

"A nanoparticle dimer plasmon ruler possesses many advantages because its measurement sensitivity is homogeneous, it can operate in the near-infrared region, and the structure's size and nanorod aspect ratio can be modified freely to get the desired measurement range and sensitivity," notes Liu.

Applications for the linear plasmon ruler extend beyond studies of optical properties of metallic nanostructures to single-molecule microscopy, surface-enhanced Raman spectroscopy, waveguiding and biosensing.

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The article, "Linear plasmon ruler with tunable measurement range and sensitivity" by Shao-Ding Liu and Mu-Tian Cheng will appear in the Journal of Applied Physics. http://jap.aip.org/resource/1/japiau/v108/i3/p034313_s1

Journalists may request a free PDF of this article by contacting jbardi@aip.org

NOTE: An image is available for journalists. Please contact jbardi@aip.org

Image Caption: In contrast to a conventional nanoparticle dimer plasmon ruler, this new one shows an approximately linear relationship between the resonance wavelength shifts and nanosphere dimer interparticle separation for a linear plasmon ruler.

ABOUT Journal of Applied Physics

Journal of Applied Physics is the American Institute of Physics' (AIP) archival journal for significant new results in applied physics; content is published online daily, collected into two online and printed issues per month (24 issues per year). The journal publishes articles that emphasize understanding of the physics underlying modern technology, but distinguished from technology on the one side and pure physics on the other. See: http://jap.aip.org/

ABOUT AIP

The American Institute of Physics is a federation of 10 physical science societies representing more than 135,000 scientists, engineers, and educators and is one of the world's largest publishers of scientific information in the physical sciences. Offering partnership solutions for scientific societies and for similar organizations in science and engineering, AIP is a leader in the field of electronic publishing of scholarly journals. AIP publishes 12 journals (some of which are the most highly cited in their respective fields), two magazines, including its flagship publication Physics Today; and the AIP Conference Proceedings series. Its online publishing platform Scitation hosts nearly two million articles from more than 185 scholarly journals and other publications of 28 learned society publishers.

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