Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
Nat Commun. 2018 Apr 12;9(1):1435. doi: 10.1038/s41467-018-03820-w.
Under ambient conditions, the behavior of a solid surface is often dominated by a molecularly thin adsorbed layer (adlayer) of small molecules. Here we develop an optical approach to unveil the nanoscale structure and composition of small-molecule adlayers on glass surfaces through spectrally resolved super-resolution microscopy. By recording the images and emission spectra of millions of individual solvatochromic molecules that turn fluorescent in the adlayer phase, we obtain ~30 nm spatial resolution and achieve concurrent measurement of local polarity. This allows us to establish that the adlayer dimensionality gradually increases through a sequence of 0D (nanodroplets), 1D (nano-lines), and 2D (films) for liquids of increasing polarity. Moreover, we find that in adlayers, a solution of two miscible liquids spontaneously demixes into nanodroplets of different compositions that correlate strongly with droplet size and location. We thus reveal unexpectedly rich structural and compositional behaviors of surface adlayers at the nanoscale.
在环境条件下，固体表面的行为通常由一层分子薄的吸附小分子（吸附层）主导。在这里，我们开发了一种光学方法，通过光谱分辨超分辨显微镜揭示玻璃表面上小分子吸附层的纳米结构和组成。通过记录数百万个在吸附层相中转荧光的溶剂化变色分子的图像和发射光谱，我们获得了约 30nm 的空间分辨率，并实现了局部极性的同时测量。这使我们能够确定吸附层的维度通过一系列的 0D（纳米液滴）、1D（纳米线）和 2D（薄膜）逐渐增加，对于极性增加的液体。此外，我们发现，在吸附层中，两种混溶性液体的溶液会自发地分离成不同组成的纳米液滴，这些液滴与液滴的大小和位置密切相关。因此，我们揭示了在纳米尺度上表面吸附层出乎意料的丰富的结构和组成行为。
