CTAB对四-(4-N-甲基吡啶)卟啉SERS谱的影响

研究了阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)对四-(4-N-甲基吡啶)卟啉(H2TMPyP)及其银配合物(AgTMPyP)在Ag胶中的表面增强拉曼散射(SERS)谱的影响.SERS光谱表明,吸附于Ag胶粒的H2TMPyP与衬底银原子结合形成AgTMPyP,加入CTAB后,部分AgTMPyP表面络合物还原为H2TMPyP.相似的去金属化反应也出现在AgTMPyP/Ag胶/CTAB体系中.CTAB的加入使SERS谱带强度明显增加.AgTMPyP的去金属化被认为是由于CTAB的存在使Ag胶颗粒表面附近微环境发生改变.

Effect of CTAB on the Surface-Enhanced Raman Scattering of Tetrakis(4-N-methylpyridyl)porphyrin

Surfactants have significant effects on the properties of liquid-solid surfaces. The effects of surfactants on the surface-enhanced Raman scattering (SERS) of molecules adsorbed on solid substrates have been used to improve the qualities of SERS spectra and to reveal the distance-enhancement relationship of SERS. On the other hand, the adsorption behaviors of porphyrin compounds on surfaces are important for their applications in electrode modification, sensitization of photo-electric transduers and biomimetic catalysis. The effect of cetyltrimethyl ammoniumbromide (CTAB) on the SERS of free-base 5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin (H2TMPyP) and its Ag-chelate (AgTMPyP) adsorbed on Ag colloid was studied. It was found from the SERS spectra that the adsorbed H2TMPyP molecules undergo silver-incorporation to form AgTMPyP which can change back toH2TMPyPwhen added CTAB. The similar demetallization reaction was aslo observed in AgTMPyP/Ag sol/CTAB systems. The SERS signals were found to be obviously enhanced when added CTAB. The implications of the findings in relation to the change ofmicro-environmenton Ag particles by the addition of CTAB are briefly discussed.