Dazzi Alexandre, Mathurin Jeremie, Leclere Philippe, Nickmilder Pierre, De Wolf Peter, Wagner Martin, Hu Qichi, Deniset-Besseau Ariane
Institut de Chimie Physique, Université Paris-Saclay─CNRS, 91400 Orsay, France.
Laboratory for Physics of Nanomaterials and Energy (LPNE), Research Institute for Materials Science and Engineering, University of Mons, 7000 Mons, Belgium.
Anal Chem. 2024 Nov 12;96(45):17931-17940. doi: 10.1021/acs.analchem.4c01969. Epub 2024 Nov 1.
Photothermal atomic force microscopy-infrared (AFM-IR) enables label-free chemical imaging and spectroscopy with nanometer-scale spatial resolution through the integration of atomic force microscopy (AFM) and infrared radiation. The capability for subsurface and three-dimensional (3D) tomographic material analysis remains, however, largely unexplored. Here, we establish a simple and robust empirical relationship between the probing depth and laser repetition rate for three important modes of AFM-IR operation: resonance-enhanced, tapping, and surface-sensitive AFM-IR. Using this empirical relationship, we demonstrate, based on the example of resonance-enhanced operation, how photothermal AFM-IR of thin surface/subsurface layers of polystyrene domains in the poly(methyl methacrylate) matrix can result in 3D representations revealing the size and thickness of small polystyrene domains in the poly(methyl methacrylate) matrix with nanometer-scale resolution. Experimental findings are confirmed by analytical models.
光热原子力显微镜-红外光谱（AFM-IR）通过整合原子力显微镜（AFM）和红外辐射，能够实现具有纳米级空间分辨率的无标记化学成像和光谱分析。然而，对于亚表面和三维（3D）断层材料分析的能力在很大程度上仍未得到充分探索。在此，我们针对AFM-IR操作的三种重要模式：共振增强模式、轻敲模式和表面敏感AFM-IR，建立了探测深度与激光重复率之间简单而稳健的经验关系。利用这一经验关系，我们以共振增强操作模式为例，展示了如何通过对聚（甲基丙烯酸甲酯）基体中聚苯乙烯域的薄表面/亚表面层进行光热AFM-IR分析，以纳米级分辨率得到揭示聚（甲基丙烯酸甲酯）基体中聚苯乙烯小域尺寸和厚度的三维图像。实验结果得到了分析模型的证实。
