Abstract
Localized Surface Plasmon Resonance (LSPR) spectroscopy of metallic nanoparticles is a powerful technique for biological sensing experiment which offers similar sensitivity to the commercially available SPR systems, with the additional advantages of wavelength tunability, smaller sensing volumes, and optical property enhancement. Our goal of this thesis is to demonstrate the LSPR wavelength tunability and the image resolution is better than SPR image. We use Nanosphere Lithography (NSL) method combined with annealing process and e-beam evaporator to fabricate various sizes and shape nanodots arrays. Various metallic nanodots including Au, Ag, Cu and Al with the triangular shape and rounded shape are created. The advantages of this process are easy-operation, low-cost, and no limitation to the use of a conducting substrate. The Localized Surface Plasmon Resonance (LSPR) spectra and images of the metallic nanostructures are obtained by using the UV-VIS spectroscopy and reconstruct our optical microscopy with TIR model. We first demonstrate the spectrum of gold which is located at 686nm within visible region. For other metals, all of them have a blue-shift compared with gold due to their higher plasma frequency. When the size of the nanodots array becomes smaller or the shape becomes rounded both of the spectra have blue-shift. For the second part, we use halogens lamp as our light source to modify our optical microscopy in order to take the TIR image which can eliminate the scattering noise from the top side, besides, it can enhance the S/N ratio. We demonstrate the Au, Ag and Al nanodots array image. We found the resolution of Al is better than Au and Ag cause of the shorter propagation length of Al.