Nano Archive

Two particle enhanced nano Raman microscopy and spectroscopy

Olk, Phillip and Renger, Jan and Hartling, Thomas and Wenzel, Marc Tobias and Eng, Lukas M. (2007) Two particle enhanced nano Raman microscopy and spectroscopy. NANO LETTERS, 7 (6). pp. 1736-1740.

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Official URL: http://dx.doi.org/10.1021/nl070727m

Abstract

The distance- and polarization-dependent near-field enhancement of two coupling metal nanoparticles (MNPs) is analyzed by means of the novel scanning particle enhanced Raman spectroscopy (SPRM) technique. In contrast to single MNP Raman experiments, the near-field coupling between two dissimilar MNPs as followed here leads to a Raman hot spot yielding an extra enhancement factor of 17.6 and 20, as proven here both in experiment and in theory. Three-dimensional electric field calculations for our two-particle arrangements were performed using the semianalytical multiple-multipole method. An excellent agreement is found to our experiments, in which we inspect the interaction between a ``scanning'' 30 nm gold MNP (Au30) and a ``fixed'' 80 nm Au MNP (Au80). The Au80 MNP is attached to the apex of an optical fiber manipulator and exposed to the Gaussian focus of a high NA = 1.45 objective at lambda = 532 nm. A monolayer of 1-octanethiol molecules covering the Au80 MNP serves as the electric field prober when scanning the Au30 MNP through the optical focus. This constellation allows recording the Raman signatures from a very low number of well-confined molecules. Moreover, also the spectral and spatial dependence could be explored with a superb sensitivity and very low integration time.

Item Type:Article
Subjects:Analytical Science > Microscopy and probe methods
Physical Science > Nanophysics
Physical Science > Nano objects
ID Code:2612
Deposited By:Anuj Seth
Deposited On:09 Jan 2009 15:52
Last Modified:20 Jan 2009 11:35

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