O'Callahan Brian T, Lewis William E, Möbius Silke, Stanley Jared C, Muller Eric A, Raschke Markus B
Opt Express. 2015 Dec 14;23(25):32063-74. doi: 10.1364/OE.23.032063.
Infrared vibrational nano-spectroscopy based on scattering scanning near-field optical microscopy (s-SNOM) provides intrinsic chemical specificity with nanometer spatial resolution. Here we use incoherent infrared radiation from a 1400 K thermal blackbody emitter for broadband infrared (IR) nano-spectroscopy. With optimized interferometric heterodyne signal amplification we achieve few-monolayer sensitivity in phonon polariton spectroscopy and attomolar molecular vibrational spectroscopy. Near-field localization and nanoscale spatial resolution is demonstrated in imaging flakes of hexagonal boron nitride (hBN) and determination of its phonon polariton dispersion relation. The signal-to-noise ratio calculations and analysis for different samples and illumination sources provide a reference for irradiance requirements and the attainable near-field signal levels in s-SNOM in general. The use of a thermal emitter as an IR source thus opens s-SNOM for routine chemical FTIR nano-spectroscopy.
基于散射扫描近场光学显微镜（s-SNOM）的红外振动纳米光谱能够提供具有纳米空间分辨率的内在化学特异性。在这里，我们使用来自1400 K热黑体发射器的非相干红外辐射进行宽带红外（IR）纳米光谱分析。通过优化的干涉外差信号放大，我们在声子极化激元光谱和阿托摩尔分子振动光谱中实现了单层灵敏度。在六方氮化硼（hBN）薄片成像及其声子极化激元色散关系的测定中展示了近场定位和纳米级空间分辨率。针对不同样品和照明源的信噪比计算与分析为一般s-SNOM中的辐照度要求和可达到的近场信号水平提供了参考。因此，使用热发射器作为红外源为常规化学傅里叶变换红外纳米光谱开启了s-SNOM的应用。
