Surface Enhanced Raman Scattering near the edge of Patterned Silver Nanoparticle films
Yi-Chen Liu1*, I-Chih Ni1, Shien-Der Tzeng1, Jiann-Yeu Chen2, Watson Kuo2,3
1Department of Physics, National Dong Hwa University, Hualien, Taiwan
2Center of Nanoscience & Nanotechnology, National Chung Hsing University, Taichung, Taiwan
3Department of Physics, National Chung Hsing University, Taichung, Taiwan
* presenting author:劉奕辰,
Silver nanostructures have large plasmonic enhancement due to their strong localized surface plasmon resonance (LSPR), which is related to their shape and size. For example, trigonal silver nanoprism has strong field enhancement near their tips for dipole resonance. But for quadrupole resonance, their enhancement region is significant at edges [1]. Further there is very strong enhancement because of LSPR coupling between nanostructures. Thus the surface enhanced Raman scattering spectrum (SERS) between nanoparticles are also stronger. However, the SERS on patterned silver nanoparticle films were never systematically studied. In this report, we observed SERS of R6G (Rhodamine 6G) on different region of patterned silver nanoparticle films. These pattern nanostructures were fabricated by the combination of centrifugal assembly method and photo or e-beem lithography method [2]. We found SERS spectrum signals of R6G molecules near edges are larger than at the center of pattern. For circular pattern, the Raman intensity (1511 cm-1 ) at the edge is about 3.7 times stronger than at the center of pattern. But the Raman background signal at the edge is about 1.7 times stronger than at the center of pattern. On the other hand, the Raman intensity at nonuniform area is stronger than uniform area. These results imply that light scattering (e.g. Raman scattering) of patterned silver nanoparticle films near edges.

[1] Kelly et al., J. Phys. Chem. B, Vol. 107, No. 3, 2003 67
[2] I-C. Ni, S.-C. Yang, C.-W. Jiang, C.-S. Luo, W. Kuo, K.-J. Lin, S.-D. Tzeng; J. Phys. Chem. C ,116, 8095. (2012)

Keywords: SERS, Silver nanostructures, pattern film