Quantitative Measurement of Local Infrared Absorption and Dielectric Function with Tip-Enhanced Near-Field Microscopy
Quantitative Measurement of Local Infrared Absorption and Dielectric Function with Tip-Enhanced Near-Field Microscopy
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DOI：
10.1021/jz400453r
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发表时间：
2013-05-02
影响因子：
5.7
通讯作者：
Hillenbrand, Rainer
中科院分区：
文献类型：
--
作者：
Govyadinov, Alexander A.;Amenabar, Iban;Hillenbrand, Rainer
散射型扫描近场光学显微镜（s-SNOM）和傅立叶变换红外纳米光谱（nano-FTIR）是新兴的纳米化学材料鉴定工具。在这里，我们通过使s-SNOM和纳米FTIR能够定量测量局部介电常数和红外吸收，进一步推动了s-SNOM和纳米FTIR的重要一步。我们的技术是基于一个分析模型，它允许一个简单的反演近场散射问题。它产生的介电常数和吸收的样品与2个数量级的空间分辨率相比，远场测量，并适用于一个大类的样品，包括聚合物和生物物质。我们验证的能力，通过确定本地的PMMA膜的介电常数从纳米FTIR测量，这是在良好的协议与远场椭偏数据。我们进一步获得本地的红外吸收光谱的峰位置和形状，这是纳米尺度上的定量化学计量学的关键前所未有的准确性。
Scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared nanospectroscopy (nano-FTIR) are emerging tools for nanoscale chemical material identification. Here, we push s-SNOM and nano-FTIR one important step further by enabling them to quantitatively measure local dielectric constants and infrared absorption. Our technique is based on an analytical model, which allows for a simple inversion of the near field scattering problem. It yields the dielectric permittivity and absorption of samples with 2 orders of magnitude improved spatial resolution compared to far field measurements and is applicable to a large class of samples including polymers and biological matter. We verify the capabilities by determining the local dielectric permittivity of a PMMA film from nano-FTIR measurements, which is in excellent agreement with far field ellipsometric data We further obtain local infrared absorption spectra with unprecedented accuracy in peak position and shape, which is the key to quantitative chemometrics on the nanometer scale.