Simulation and Verification Raman Enhancement with Silver and Gold Grating
Date Issued
2011
Date
2011
Author(s)
Lee, Cheng-Han
Abstract
Raman scattering enhancement has been a popular research topic and applied to various fields such as biological protein research and medical immune examination. Raman scattering have the character of rapidly and precisely analyzing molecular structure. Moreover, new techniques of Raman scattering have constantly been invented including surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS) etc. However, there is no research dealing with quantifying the effect of Raman enhancement, that is to say that the enhancement of Raman signal cannot be quantitatively determined. Therefore, under proper experimental environment and gauging skills, the research aims to quantify the enhancement of Raman signal using our lab’s newly developed Optical Computing Method.
The newly developed Optical Computing Method is to simulate periodic grating structure first. We found that grating due to their different materials, different line width period, depth, or different dielectric constant of measuring target, which lead to different local electromagnetic field distribution around grating. By simulating grating structure, we discover a grating environment which can enhance signal. Because of the large dielectric constant of water, making water into the trench of grating will restrict the vertical incident light within the water. The indecent energy will generate resonance in the water and thereby enhance signal. The more detailed phenomena are articulated in the thesis. Based on the simulation, I designed a real-time gauging method to create the simulated condition. During the experiment, I noticed that the self-assemble monolayer (SAM )on the surface of grating influences the effect of Raman enhancement. Therefore, I produced compound on the surface of golden grating and silver grating respectively and cover them by water. Doing the Raman real-time gauging in the aforementioned environment successfully generated the result of signal enhancement.
Subjects
Raman scattering enhancement
grating
optical computing method
resonance
self-assemble monolayer
Type
thesis
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