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Originally published in Science Express on 26 June 2008
Science 18 July 2008:
Vol. 321. no. 5887, pp. 388 - 392
DOI: 10.1126/science.1159499
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Reports

Measurement of the Distribution of Site Enhancements in Surface-Enhanced Raman Scattering

Ying Fang,* Nak-Hyun Seong,* Dana D. Dlott{dagger}

On nanotextured noble-metal surfaces, surface-enhanced Raman scattering (SERS) is observed, where Raman scattering is enhanced by a factor, G, that is frequently about one million, but underlying the factor G is a broad distribution of local enhancement factors, {eta}. We have measured this distribution for benzenethiolate molecules on a 330-nanometer silver-coated nanosphere lattice using incident light of wavelength 532 nanometers. A series of laser pulses with increasing electric fields burned away molecules at sites with progressively decreasing electromagnetic enhancement factors. The enhancement distribution P({eta})d{eta} was found to be a power law proportional to ({eta})–1.75, with minimum and maximum values of 2.8 x 104 and 4.1 x 1010, respectively. The hottest sites ({eta} >109) account for just 63 in 1,000,000 of the total but contribute 24% to the overall SERS intensity.

School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

* These authors contributed equally to this work.

{dagger} To whom correspondence should be addressed. E-mail: dlott{at}scs.uiuc.edu

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Science. ISSN 0036-8075 (print), 1095-9203 (online)