Hybrid Gold-Conductive Metal Oxide Films for Attenuated Total Reflectance Surface Enhanced Infrared Absorption Spectroscopy
Hybrid Gold-Conductive Metal Oxide Films for Attenuated Total Reflectance Surface Enhanced Infrared Absorption Spectroscopy
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DOI：
10.1021/acsanm.8b02155
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发表时间：
2019-03-01
影响因子：
5.9
通讯作者：
Burgess, Ian J.
中科院分区：
文献类型：
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作者：
Andvaag, Ian R.;Morhart, Tyler A.;Burgess, Ian J.
对导电金属氧化物（CMO）膜作为衰减全反射表面增强红外吸收光谱（ATR-SEIRAS）的支撑层进行了理论和实验研究。通过红外反射率测量和Drude模型验证了氧化铟锌（IZO）薄层与金属相比具有更高的中红外透射率。IZO层溅射在硅微机械内反射元件（Si μ IRES）被发现有一个薄的表面层与稍有不同的等离子体频率和电子散射时间相比，散装材料。IZO的复介电常数和折射率可以使用Drude模型提取。这允许应用Bruggeman有效介质理论来计算支持在IZO膜上的一层金扁长球体的ATR-SEIRAS响应。计算的ATR-SEIRAS光谱为1 nm厚的有机膜，建模为洛伦兹振荡器，预测的数量级的改善，吸收强度使用IZO膜作为基层相比，传统的，覆盖金的内反射元件。这些预测定性验证了电沉积金纳米粒子上的IZO改性的Si内反射元件和电位控制的吸附的吡啶衍生物的研究。IZO/Au层被发现是非常机械稳定的，可以承受大的潜在的扰动。这是证明通过在原位研究的4-巯基苯甲酸的自组装单层的重复还原解吸。
The use of conductive metal oxide (CMO) films as supporting layers for attenuated total reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) is treated theoretically and experimentally. The greater mid-infrared transparency of thin layers of indium zinc oxide (IZO), as compared to metals, is verified through IR reflectivity measurements and the Drude model. IZO layers sputtered on silicon micromachined internal reflection elements (Si mu IREs) are found to have a thin surface layer with slightly different plasma frequency and electronic scattering time compared to the bulk material. The complex permittivity and refractive index of the IZO can be extracted using the Drude model. This allows application of the Bruggeman effective medium theory to calculate the ATR-SEIRAS response of a layer of gold prolate spheroids supported on an IZO film. Calculated ATR-SEIRAS spectra for a 1 nm thick organic film, modeled as a Lorentz oscillator, predict an order of magnitude improvement in absorbance strength using the IZO film as a base layer compared to a conventional, gold covered internal reflection element. These predictions are qualitatively verified by the electrodeposition of gold nanoparticles on an IZO modified Si internal reflection element and the study of the potential controlled adsorption of a pyridine derivative. The IZO/Au layers are found to be very mechanically stable and can withstand large potential perturbations. This is demonstrated through the in situ study of the repeated reductive desorption of a self assembled monolayer of 4-mercaptobenzoic acid.