Open AccessOptical characterization of surface adlayers and their compositional demixing at the nanoscale
Author(s) -
Limin Xiang,
Michal Wojcik,
Samuel J. Kenny,
Rui Yan,
Seonah Moon,
Wan Li,
Ke Xu
Publication year - 2018
Publication title -
nature communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.559
H-Index - 365
ISSN - 2041-1723
DOI - 10.1038/s41467-018-03820-w
Subject(s) - nanoscopic scale , characterization (materials science) , materials science , nanotechnology , surface (topology) , chemical physics , chemistry , geometry , mathematics
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.