Surface enhanced Raman scattering observed using Ag-TiO2 nano-structured powder from the photoreduction of AgNO3 with visible-light activated TiO2

• Main Authors: Zih-Ci Hong, 洪子奇
• Other Authors: Chia-Liang Cheng
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/6gr245

碩士 === 國立東華大學 === 光電工程研究所 === 96 === In this thesis, the effect of Surface enhanced Raman scattering (SERS) on nanodiamond and titanium dioxide (TiO2) was investigated using silver as SERS-active substrate. The noble metals used for SERS measurement are usually deposited by vapor deposition. In this study, nanostructured silver was photoreduced from silver nitrate (AgNO3) using TiO2 as photocatalyst. UV-activated and visible light-activated carbon-containing TiO2 were used as photocatalyst to prepare silver nanostructures. The morphology of nanostructured silver obtained with two different TiO2 samples is observed with SEM-imaging and compared. It can be seen clearly that the distribution of silver photoreduced by UV-activated TiO2 is more homogeneous than by visible light-activated TiO2. Using photoreduced silver as SERS-active substrate observed good enhancement of Raman signals of TiO2 rutile phase, carbon from carbon-containing TiO2 as well as from added 100 nm diamond powder. For carbon region of Raman spectra, the enhancement is about 10 times after silver deposition. The properties of TiO2 can also be researched with SERS. It can be seen clearly that together with anatase phase peak of visible-light activated carbon-containing TiO2, the rutile peaks become more significant after silver deposition. This result is presumably due to the mixed phase structure of carbon-containing TiO2. It is known from literature that rutile phase Raman peaks demonstrate SERS, while observations of SERS from anatase are not discussed. Therefore, our experiment will concentrate on SERS research from anatase phase of visible light-activated carbon-containing TiO2. It can be proved that SERS using photoreduced silver as active substrate provides information concerning the structure peculiarities of carbon-containing TiO2 which are too negligible to be detected with other method. It also allows observing characteristics of nanodiamond and distinguishes them from carbon contaioned in visible-light active TiO2.