The high‐contrast optical imaging of nearly transparent 2D materials such as clays and some oxide sheets has been an outstanding challenge; yet there is a critical research capability needed in the synthesis and processing of these materials, which show promise in a number of applications including barrier coatings, membranes, and composites. Using delaminated silicate clay and titania sheets as model systems, here it is shown that these weakly quenching, nearly transparent 2D sheets can be readily imaged by fluorescence quenching microscopy (FQM) based on a new mechanism. When these sheets are deposited on strongly quenching substrates, including doped silicon wafers and metals or indium tin oxide‐coated glass slides, they can act as a “spacer” to reduce the degree of quenching of the dye layer by the substrate, appearing as highly visible bright sheets against a dark background. This new FQM strategy can visualize dielectric 2D materials with high contrast and layer resolutions comparable to scanning electron microscopy and atomic force microscopy. When different 2D materials are co‐deposited, FQM not only differentiates them readily based on their quenching capabilities, but also can resolve their vertical stacking sequence based on the contrast of their overlapped areas.

中文翻译：

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通过荧光淬灭显微镜观察透明的二维片材

几乎透明的2D材料（如粘土和一些氧化物片）的高对比度光学成像一直是一项艰巨的任务。然而，在这些材料的合成和加工中还需要关键的研究能力，这在阻隔涂料，膜和复合材料等许多应用中显示出了希望。使用分层的硅酸盐粘土和二氧化钛薄板作为模型系统，这里表明这些弱淬灭，近乎透明的2D薄片可以通过基于新机理的荧光淬灭显微镜（FQM）轻松成像。当这些片材沉积在强淬火的基材（包括掺杂的硅片和金属或涂有氧化铟锡的玻璃载片）上时，它们可以充当“隔离剂”，以减少基材对染料层的淬灭程度，在深色背景下显示为高度可见的亮片。这种新的FQM策略可以可视化具有与扫描电子显微镜和原子力显微镜相当的高对比度和层分辨率的2D介电材料。当共存不同的2D材料时，FQM不仅可以根据其淬火能力轻松地区分它们，还可以根据其重叠区域的对比度来解析其垂直堆叠顺序。