表面增强拉曼光谱研究正己硫醇分子在银基底表面自组装过程的时间和浓度因素影响

A SERS Study on Self-Assembly Process of 1-Hexanethiol on Ag Nanoparticles:Effects on Adsorption Time and Concentration

表面增强拉曼光谱(SERS)是一种具有超灵敏检测能力的谱学技术,可以在单分子水平上检测分子结构的动态变化过程。烷基硫醇的自组装膜是一类典型的类晶态有序结构薄膜,在仿生、材料、电子和化学等领域有着重要的应用,越来越受到人们的关注。本文利用SERS对正己硫醇(hexanethiol,HT)分子在银基底上的吸附和组装过程进行研究,对HT的拉曼和自组装膜SERS光谱进行了指认。根据C—S,C—C和CH3键结构的反式和旁式的特征光谱信息,研究HT吸附在银纳米粒子表面的构象,以及自组装膜结构的有序性。研究了吸附时间和浓度两个因素对成膜规律产生的影响。实验结果表明,当HT溶液浓度较高时,HT单层膜成膜速率较快,且有序性较好;当HT溶液浓度较低时,HT单层膜成膜速率较慢,且有序性较差。这一研究结果对成膜动力学以及烷基硫醇的有序单层膜的制备具有重要的指导意义,为基于烷基硫醇的自组装单层膜在防腐、器件和生物方面的应用奠定了基础。

Surface-enhanced Raman scattering（SERS）is an ultra-sensitive spectroscopic technique which has great application prosepct in characterization of dynamic molecular structures.Self-assembled monolayers（SAMs）of alkanethiolates are a typical kind of ultrathin films which have tremendous applications in the fields of bionics,materials,electronics,biology and chemistry.In the present study,the SAM structures of 1-hexanethiol when adsorbing on Ag nanoparticles were explored.The vibrational modes of trans（T）and gauche（G）conformations were employed to illustrate the molecular structures.The intensity ratios of T and G bands concerning to C—S,C—C and CH3 groups indicate the crystallinity of the SAMs.The results show that when HT is in high concentrations the crystalline process is quick,while in low concentrations,the crystalline process is very slow.The dynamic study on the formation of SAM films is of great significance for the corrosion protection,device fabrication,and sensor applications.