The Influences of Silver Particle Size and Excitation Wavelength on the Surface Enhanced Raman Scattering

• Main Authors: Kun-Hong Cheng, 鄭坤泓
• Other Authors: Y. T. Lee
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/95245618094314502282

碩士 === 逢甲大學 === 光電研究所 === 96 === By changing the concentrations of silver nitrate solutions and reducing agents (sodium borohydride),we could obtain the silver particles with sizes ranging from 8nm to 78nm and observe the particle’s size-effect on the Surface Enhanced Raman Scattering (SERS) of benzoic acid(BA) solutions excited by six laser wavelengths(476nm~633nm). The BA is dissolved in methanol and kept at the concentration 10-2 M。We analyzed the intensities of BA’s 1003 cm-1 and 1600 cm-1 vibrational modes relative to the 1033 cm-1 vibrational mode of methanol. The observed size-dependences of SERS intensities fit quite well with those calculated by the Schatz’s theoretical model for the spherical silver nanoparticles. The only exception occurred for the cases with the smallest particles (8nm), possibly due to the failure of Maxwell EM theories used in this model. As predicted by Schatz’s model, our experimental results of BA’s SERS intensity exhibit a maximum at the optimum excitation wavelength for either small or large silver nanoparticles. However, the optimum wavelengths deviate quantitatively from the theoretical estimations.