Transmission X-ray scattering as a probe for complex liquid-surface structures
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- 作者：Masafumi Fukuto ; Lin Yang ; Dmytro Nykypanchuk and Ivan Kuzmenko
- 关键词：transmission X-ray scattering ; liquid surface scattering ; SAXS ; WAXS ; air/water interface
- 刊名：Journal of Synchrotron Radiation
- 出版年：2016
- 出版时间：March 2016
- 年：2016
- 卷：23
- 期：2
- 页码：519-531
- 全文大小：1955K
- ISSN：1600-5775
文摘
The need for functional materials calls for increasing complexity in self-assembly systems. As a result, the ability to probe both local structure and heterogeneities, such as phase-coexistence and domain morphologies, has become increasingly important to controlling self-assembly processes, including those at liquid surfaces. The traditional X-ray scattering methods for liquid surfaces, such as specular reflectivity and grazing-incidence diffraction, are not well suited to spatially resolving lateral heterogeneities due to large illuminated footprint. A possible alternative approach is to use scanning transmission X-ray scattering to simultaneously probe local intermolecular structures and heterogeneous domain morphologies on liquid surfaces. To test the feasibility of this approach, transmission small- and wide-angle X-ray scattering (TSAXS/TWAXS) studies of Langmuir films formed on water meniscus against a vertically immersed hydrophilic Si substrate were recently carried out. First-order diffraction rings were observed in TSAXS patterns from a monolayer of hexagonally packed gold nanoparticles and in TWAXS patterns from a monolayer of fluorinated fatty acids, both as a Langmuir monolayer on water meniscus and as a Langmuir–Blodgett monolayer on the substrate. The patterns taken at multiple spots have been analyzed to extract the shape of the meniscus surface and the ordered-monolayer coverage as a function of spot position. These results, together with continual improvement in the brightness and spot size of X-ray beams available at synchrotron facilities, support the possibility of using scanning-probe TSAXS/TWAXS to characterize heterogeneous structures at liquid surfaces.