%0 Journal Article
%T Investigation of 1D Siliver Nanoparticle Arrays for Use as Molecule Concentration-Specific SERS Substrates
%A Jun Gao
%A Huan Qian
%A Shang Xu
%A Min Han
%J Journal of Nanomaterials
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/989803
%X One-dimensional arrays of silver nanoparticles with a particle size of 10.5£¿nm and interparticle spacing of 8.5£¿nm were fabricated by depositing nanoparticles in gas phase on block copolymer self-assembled templates. The substrate showed a surface-enhanced Raman scattering (SERS) enhancement factor as high as with good reproducibility and stability. The dependence of the average enhancement factor and the SERS intensity on the packing density of the analyte molecules were investigated. For a tiny amount of analytes in the range of to £¿mol/mm2, the SERS signal showed a linear dependence on the molecule packing density on a logarithmic scale, with a slope of about 1.25. The substrates are promising for quantitative detection of trace level molecules. 1. Introduction The last three decades have witnessed an ever-increasing interest in surface-plasmon-based analytical techniques, of which surface-enhanced Raman scattering (SERS) [1¨C5] is one of the most important applications. However, the rational design and facile fabrication of reproducible SERS substrates with large and stable enhancement of Raman signals remain a critical challenge [6, 7]. Despite that extensive efforts have been devoted to the local field enhancement and single molecule detection at the hot spots, less attention has been paid to the average enhancement factor , which has greater relevance for the design and optimization of SERS-based chemical sensors [8, 9]. Metal nanoparticle assemblies are important substrates for SERS-based molecule sensing, because of the light confinement between nanoparticles, which provides enhanced local electromagnetic fields and the tunability of localized surface plasmon resonances. To enable molecule detection in high SERS activity, stability and reproducibility, a knowledge of the arrangement of the analyte molecules and hot spots, and their effects to the average enhancement are important. To obtain a large average enhancement, it is crucial to provide a state of aggregation of the metal nanoparticles and to place the analyte molecules in the sites of the junctions of metal nanoparticles. In this sense, one- and two-dimensional ordered arrays of closely spaced metal nanoparticles can be excellent candidates for SERS substrates. They can provide not only giant field enhancement both through long range photonic coupling and the local electromagnetic near field confinement, but also high reproducibility because of the uniform and dense distribution of hot spots. Recently, block copolymer self-assembled nanopatterns were used as templates to fabricate high
%U http://www.hindawi.com/journals/jnm/2013/989803/