The study of Benzoic acid and P-hydroxybenzoic acid by SERS

• Main Authors: Ruei-you Wong, 翁瑞佑
• Other Authors: Ying-te Lee
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/23401910955386252355

碩士 === 逢甲大學 === 光電研究所 === 99 === In this work, we studied the surface enhanced Raman scattering (SERS) of carboxyl and benzene ring’s vibrational modes of benzoic acid (BA) and p-hydroxybenzoic acid (PHBA) dissolved, respectively, in the methanol at the concentration range from 0.008M to 0.6M. All three vibrational modes’ SERS of BA have similar concentration dependence, with the maximum at around 0.05M. However, those of PHBA only monotonically increase with its concentration. These results are interpreted as the different surface orientation. These phenomena were interpreted as the result of different adsorption orientation of BA and PHBA on the silver nanoparticles, with the former to be vertically adhered on the Ag surface, and the latter tends to lie flat on the surface. The BA’s SERS was expected to increase as its concentration is increasing initially. However, at higher concentrations, its SERS will start to decline due to the impact in between the overcrowded adsorbed BA molecules. Based on this peculiar SERS dependence on the BA concentration, we can probably estimate the nanoparticle’s coverage for the best SERS (? 63%) and even design a Raman spectral method in determining the size of nanoparticles.