Two Particle Enhanced Nano Raman Microscopy and Spectroscopy
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- 作者：Phillip Olk ; Jan Renger ; Thomas Hä ; rtling ; Marc Tobias Wenzel ; Lukas M. Eng
- 刊名：Nano Letters
- 出版年：2007
- 出版时间：June 2007
- 年：2007
- 卷：7
- 期：6
- 页码：1736 - 1740
- 全文大小：174K
- 年卷期：v.7,no.6(June 2007)
- ISSN：1530-6992
文摘
The distance- and polarization-dependent near-field enhancement of two coupling metal nanoparticles (MNPs) is analyzed by means of thenovel scanning particle enhanced Raman spectroscopy (SPRM) technique. In contrast to single MNP Raman experiments, the near-field couplingbetween two dissimilar MNPs as followed here leads to a Raman hot spot yielding an extra enhancement factor of 17.6 and 20, as proven hereboth in experiment and in theory. Three-dimensional electric field calculations for our two-particle arrangements were performed using thesemianalytical multiple-multipole method. An excellent agreement is found to our experiments, in which we inspect the interaction betweena "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 manipulatorand exposed to the Gaussian focus of a high NA = 1.45 objective at 
= 532 nm. A monolayer of 1-octanethiol molecules covering the Au80MNP serves as the electric field prober when scanning the Au30 MNP through the optical focus. This constellation allows recording theRaman signatures from a very low number of well-confined molecules. Moreover, also the spectral and spatial dependence could be exploredwith a superb sensitivity and very low integration time.
= 532 nm. A monolayer of 1-octanethiol molecules covering the Au80MNP serves as the electric field prober when scanning the Au30 MNP through the optical focus. This constellation allows recording theRaman signatures from a very low number of well-confined molecules. Moreover, also the spectral and spatial dependence could be exploredwith a superb sensitivity and very low integration time.