In situ surface-enhanced infrared absorption spectroscopy for the analysis of the adsorption and desorption process of Au nanoparticles on the SiO2/Si surface
In situ surface-enhanced infrared absorption spectroscopy for the analysis of the adsorption and desorption process of Au nanoparticles on the SiO2/Si surface
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DOI：
10.1021/la063239n
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发表时间：
2007-05-22
期刊：
影响因子：
3.9
通讯作者：
Aono, Masakazu
中科院分区：
文献类型：
--
作者：
Enders, Dominik;Nagao, Tadaaki;Aono, Masakazu
采用液体流动池原位衰减全反射表面增强红外吸收（ATR-SEIRA）技术研究了胶体D2O悬浮液中Au纳米粒子（AuNP）在（3-氨基丙基）三乙氧基硅烷处理的SiO2/Si表面的吸附和解吸。随着AuNP表面密度的增加，由于SEIRA作用，覆盖在AuNP表面的D2O和柠檬酸盐分子的振动模式的吸收增加。AuNP之间的排斥静电库仑力导致AuNP表面密度在亚单层覆盖处饱和。我们发现可以通过原位监测D2O和柠檬酸盐分子的分子振动模式来研究吸附动力学。此外，我们澄清了吸附过程可以很好地描述扩散限制的一阶Langmuir动力学模型。当将饱和的AuNP亚单层暴露于2-氨基乙硫醇(AET)/D2O溶液中时，AuNP从表面去除，D2O振动模式的红外吸收再次变弱。考虑到OD和CH峰的时间依赖性，我们提出了一个微观模型，其中AET分子通过取代暴露在AET溶液中的大部分覆盖柠檬酸盐分子，快速吸附在AuNP上。当这个过程发生时，我们可以用扫描电子显微镜检测到的AuNP团块最终从表面移除。
The adsorption and desorption of Au nanoparticles (AuNP) in colloidal D2O suspension on the (3-aminopropyl)triethoxysilane treated SiO2/Si surface was investigated by in situ attenuated total reflection surface enhanced infrared absorption (ATR-SEIRA) spectroscopy with a liquid flow cell. With increasing surface density of AuNP, the absorption of the vibrational modes of D2O and of the citrate molecules covering the AuNP increases due to SEIRA. Repulsive electrostatic Coulomb forces between the AuNP lead to the saturation of the AuNP surface density at submonolayer coverage. We show that the adsorption kinetics can be investigated by monitoring in situ the molecular vibrational modes of D2O and the citrate molecules. Furthermore, we clarify that the adsorption process can be described very well by a diffusion-limited first-order Langmuir kinetics model. When exposing a saturated AuNP submonolayer to 2-aminoethanethiol (AET)/D2O solution, the AuNP are removed from the surface and the IR absorption of the D2O vibrational modes become weaker again. Taking into account the time dependencies of the OD and the CH peaks, we propose a microscopic model where the AET molecules quickly adsorb on the AuNP by replacing most of the precovering citrate molecules exposed to the AET solution. As this takes place, the AuNP agglomerateas we could detect with scanning electron microscopyand are finally removed from the surface.