Metallic nanoparticles covered on the decorated hyperbolic metamaterial substrate for Surface Enhanced Raman Scattering
| Autor: | Wang,Guo-An, 王國安 |
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| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 In this thesis, wemainly used centrifugal method to arrange gold,silver, and unique star-shaped gold nanoparticles on silver-aluminum oxide substrate and Ge-Ag hyperbolic metamaterial substrate to fabricate the SERS substrate. Then, we employed these substrates to measure the Raman spectrum of molecules with different excitation wavelengths, including 532nm and 1064nm, to observe the effect of different metal nanoparticles generated in different excitation wavelength. And we used COMSOL multiphysics software to simulate SERS substrate’s absorborption and distribution of electric field intensity when the nanoparticles were aggregated. We found that the absorption spectrum peak of nanoparticle will be red-shifted and enhanced as nanoparticle aggregation occurs. When the laser excited at 532nm, we found that the Raman intensity of molecules adsorbed on silver nanoparticles over ALD substrates is greater than that adsorbed on silver nanoparticles over HMM substrate. That is due to coupling occurs when the substrate’s absorborption is very close to silver nanoparticle’s absorborption. On the other hand, star-shaped nanoparticle’s signal intensity is greater than gold nanoparticles under 1064nm Raman spectrum, that is because of the absorption spectrum peak of star-shaped nanoparticles at 974nm,which are very close to the laser wavelength, the surface plasma phenomena would be more stronger. Finally, we counted the number density of nanoparticles by using image J software and calculate the Raman spectra contributed from each nanoparticle. We found that the star-shaped nanoparticle’s signal intensity is greater than gold and silver nanoparticles under 1064nm Raman spectrum in the same density. On the ALD substrate, the Raman intensity of molecules adsorbed on mstar-shaped nanoparticles enhanced approximately 5.48 times than that adsorbed on gold nanoparticles under 1064nm Raman spectrum in the same density; the Raman intensity of molecules adsorbed on siliver nanoparticles enhanced approximately 1.49 times than that adsorbed on gold nanoparticles under 1064nm Raman spectrum in the same density. On the HMM substrate, the Raman intensity of molecules adsorbed on star-shaped nanoparticles enhanced approximately 7.17 times than that adsorbed on gold nanoparticles under 1064nm Raman spectrum in the same density; the Raman intensity of molecules adsorbed on siliver nanoparticles enhanced approximately 1.22 times than that adsorbed on gold nanoparticles under 1064nm Raman spectrum in the same density. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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