Raman enhancement of rhodamine adsorbed on Ag nanoparticles self-assembled into nanowire-like arrays
1 Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Zografou Campus, Zografou, Athens 157 80, Greece
2 Department of Electronics, Technological Educational Institute of Athens, 12210 Aegaleo, Greece
3 North University of China, Taiyuan, Shanxi, People's Republic of China
4 Institute of Microelectronics, NCSR "Demokritos", GR 15310 Ag. Paraskevi Greece
Nanoscale Research Letters 2011, 6:629 doi:10.1186/1556-276X-6-629Published: 14 December 2011
This work reports on Raman scattering of rhodamine (R6G) molecules absorbed on either randomly distributed or grating-like arrays of approximately 8-nm Ag nanoparticles developed by inert gas aggregation. Optimal growth and surface-enhanced Raman scattering (SERS) parameters have been obtained for the randomly distributed nanoparticles, while effects related to the aging of the silver nanoparticles were studied. Grating-like arrays of nanoparticles have been fabricated using line arrays templates formed either by fracture-induced structuring or by standard lithographic techniques. Grating structures fabricated by both methods exhibit an enhancement of the SERS signal, in comparison to the corresponding signal from randomly distributed Ag nanoparticles, as well as a preferential enhancement in the areas of the sharp features, and a dependence on the polarization direction of the incident exciting laser beam, with respect to the orientation of the gratings structuring. The observed spectroscopic features are consistent with a line-arrangement of hot-spots due to the self- alignment of metallic nanoparticles, induced by the grating-like templates.