| dc.description.abstract | This study investigated the effect of ZnO nanorods decorated with metallic nanoparticles on surface enhanced Raman scattering(SERS). ZnO has two crystalline structures, i.e. the hexagonal wurtzite structure and the cubic sphalerite structure. These two structures are of symmetric lattices and thus exhibit piezoelectric characteristics, be useful in the applications on surface acoustic wave devices, gas detectors, etc. In order to produce a SERS-active substrate, we employ a low-temperature hydrothermal method to synthesize large-area and uniform ZnO nanorods on silicon substrates . To attain the localized surface plasma resonance (LSPR) effect, we deposit a thin metal film on the nanorods, and use an annealing process to produce metal nanoparticles. The LSPR effect leads to the ＂hot spots＂ between adjacent metal nanoparticles, rendering greatly amplified Raman scattering intensities. The amplified SERS intensities can be used to determine the concentrations of fluorescent molecules.
Different metal thicknesses (10, 20, 30, 40, and 50nm) on the ZnO-nanorod SERS substrate were firstly investigated to maximized the Raman scattering intensity. And then the effect of annealing temperature was studied with the optimized metal thickness.
In order to evaluate the lowest detectable molecule concentration, we prepared the R6G (rhodamine 6G) solutions with different concentrations. The lowest detectable concentration was found to be 10-9 M, whereas the flat substrate gave the lowest detectable concentration of 10-3 M. Enhancement factor is 1.5×104. The result confirms that the ZnO-nanorod SERS substrate is effective in enhancing the Raman scattering intensity of fluorescent molecules. | en_US |