Atomic force microscopy-infrared microscopy (AFM-IR) provides a route to bypass Abbe’s diffraction limit through photothermal detections of infrared absorption. With the combination of total internal reflection, AFM-IR can operate in the aqueous phase. However, AFM-IR in contact mode suffers from surface damage from the lateral shear force between the tip and sample, and can only achieve 20~25-nm spatial resolution. Here, we develop the liquid-phase peak force infrared (LiPFIR) microscopy that avoids the detrimental shear force and delivers an 8-nm spatial resolution. The non-destructiveness of the LiPFIR microscopy enables in situ chemical measurement of heterogeneous materials and investigations on a range of chemical and physical transformations, including polymer surface reorganization, hydrogen-deuterium isotope exchange, and ethanol-induced denaturation of proteins. We also perform LiPFIR imaging of the budding site of yeast cell wall in the fluid as a demonstration of biological applications. LiPFIR unleashes the potential of in liquid AFM-IR for chemical nanoscopy.

中文翻译：

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液相峰力红外显微镜

原子力显微镜-红外显微镜（AFM-IR）提供了通过光热检测红外吸收来绕过阿贝衍射极限的途径。结合全内反射，AFM-IR可以在水相中运行。但是，AFM-IR处于接触模式时会受到尖端与样品之间的横向剪切力的破坏，只能获得20〜25 nm的空间分辨率。在这里，我们开发了液相峰值力红外（LiPFIR）显微镜，该显微镜避免了有害的剪切力并提供了8 nm的空间分辨率。LiPFIR显微镜的非破坏性可实现原位异质材料的化学测量以及一系列化学和物理转变的研究，包括聚合物表面重组，氢-氘同位素交换和乙醇诱导的蛋白质变性。我们还对液体中酵母细胞壁的出芽部位进行LiPFIR成像，以证明其生物学应用。LiPFIR释放了液体AFM-IR在化学纳米技术中的潜力。