News Column

Findings from University of California Yields New Findings on Fullerenes

June 27, 2014

By a News Reporter-Staff News Editor at Science Letter -- Fresh data on Fullerenes are presented in a new report. According to news reporting originating in Berkeley, California, by NewsRx journalists, research stated, "Optical absorption is the most fundamental optical property characterizing light-matter interactions in materials and can be most readily compared with theoretical predictions. However, determination of optical absorption cross-section of individual nanostructures is experimentally challenging due to the small extinction signal using conventional transmission measurements."

The news reporters obtained a quote from the research from the University of California, "Recently, dramatic increase of optical contrast from individual carbon nanotubes has been successfully achieved with a polarization-based homodyne microscope, where the scattered light wave from the nanostructure interferes with the optimized reference signal (the reflected/transmitted light). Here we demonstrate high-sensitivity absorption spectroscopy for individual single-walled carbon nanotubes by combining the polarization-based homodyne technique with broadband super-continuum excitation in transmission configuration. To our knowledge, this is the first time that high-throughput and quantitative determination of nanotube absorption cross-section over broad spectral range at the single-tube level was performed for more than 50 individual chirality-defined single-walled nanotubes. Our data reveal chirality-dependent behaviors of exciton resonances in carbon nanotubes, where the exciton oscillator strength exhibits a universal scaling law with the nanotube diameter and the transition order. The exciton linewidth (characterizing the exciton lifetime) varies strongly in different nanotubes, and on average it increases linearly with the transition energy. In addition, we establish an empirical formula by extrapolating our data to predict the absorption cross-section spectrum for any given nanotube."

According to the news reporters, the research concluded: "The quantitative information of absorption cross-section in a broad spectral range and all nanotube species not only provides new insight into the unique photophysics in one-dimensional carbon nanotubes, but also enables absolute determination of optical quantum efficiencies in important photoluminescence and photovoltaic processes."

For more information on this research see: Systematic determination of absolute absorption cross-section of individual carbon nanotubes. Proceedings of the National Academy of Sciences of the United States of America, 2014;111(21):7564-7569. Proceedings of the National Academy of Sciences of the United States of America can be contacted at: Natl Acad Sciences, 2101 Constitution Ave NW, Washington, DC 20418, USA. (National Academy of Sciences -; Proceedings of the National Academy of Sciences of the United States of America -

Our news correspondents report that additional information may be obtained by contacting K.H. Liu, University of California, Lawrence Berkeley Natl Lab, Berkeley, CA 94720, United States. Additional authors for this research include X.P. Hong, S. Choi, C.H. Jin, R.B. Capaz, J. Kim, W.L. Wang, X.D. Bai, S.G. Louie, E.G. Wang and F. Wang (see also Fullerenes).

Keywords for this news article include: Berkeley, California, Fullerenes, United States, Nanotechnology, Carbon Nanotubes, Emerging Technologies, North and Central America

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Source: Science Letter

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