Wang Le, Wang Haomin, Wagner Martin, Yan Yong, Jakob Devon S, Xu Xiaoji G
Department of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, PA 18015, USA.
Bruker Nano, 112 Robin Hill Road, Santa Barbara, CA 93117, USA.
Sci Adv. 2017 Jun 23;3(6):e1700255. doi: 10.1126/sciadv.1700255. eCollection 2017 Jun.
Nondestructive chemical and mechanical measurements of materials with ~10-nm spatial resolution together with topography provide rich information on the compositions and organizations of heterogeneous materials and nanoscale objects. However, multimodal nanoscale correlations are difficult to achieve because of the limitation on spatial resolution of optical microscopy and constraints from instrumental complexities. We report a novel noninvasive spectroscopic scanning probe microscopy method-peak force infrared (PFIR) microscopy-that allows chemical imaging, collection of broadband infrared spectra, and mechanical mapping at a spatial resolution of 10 nm. In our technique, chemical absorption information is directly encoded in the withdraw curve of the peak force tapping cycle after illumination with synchronized infrared laser pulses in a simple apparatus. Nanoscale phase separation in block copolymers and inhomogeneity in CHNHPbBr perovskite crystals are studied with correlative infrared/mechanical nanoimaging. Furthermore, we show that the PFIR method is sensitive to the presence of surface phonon polaritons in boron nitride nanotubes. PFIR microscopy will provide a powerful analytical tool for explorations at the nanoscale across wide disciplines.
对具有约10纳米空间分辨率的材料进行无损化学和机械测量，并结合形貌分析，可提供有关异质材料和纳米级物体的组成与结构的丰富信息。然而，由于光学显微镜空间分辨率的限制以及仪器复杂性带来的约束，多模态纳米级相关性难以实现。我们报道了一种新型的非侵入式光谱扫描探针显微镜方法——峰值力红外（PFIR）显微镜，它能够以10纳米的空间分辨率进行化学成像、收集宽带红外光谱以及机械测绘。在我们的技术中，在一个简单的装置中，用同步红外激光脉冲照射后，化学吸收信息直接编码在峰值力敲击循环的回撤曲线中。利用相关的红外/机械纳米成像技术研究了嵌段共聚物中的纳米级相分离以及CHNHPbBr钙钛矿晶体中的不均匀性。此外，我们表明PFIR方法对氮化硼纳米管中表面声子极化激元的存在敏感。PFIR显微镜将为跨广泛学科的纳米级探索提供一个强大的分析工具。
