Optical Imaging of Surface Chemistry and Dynamics in Confinement

The interfacial structure and dynamics of water in a microscopically confined geometry is imaged in three dimensions and on millisecond time scales. We developed a 3D wide-field second harmonic microscope that employs structured illumination. We image pH induced chemical changes on the curved and co...

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Bibliographic Details
Published in:arXiv.org 2017-07
Main Authors: Macias-Romero, Carlos, Nahalka, Igor, Okur, Halil I, Roke, Sylvie
Format: Article
Language:English
Subjects:
Aqueous solutions
Catalysis
Dipole interactions
Electric fields
Electrochemistry
Image contrast
Organic chemistry
Silicon dioxide
Water chemistry
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Summary:The interfacial structure and dynamics of water in a microscopically confined geometry is imaged in three dimensions and on millisecond time scales. We developed a 3D wide-field second harmonic microscope that employs structured illumination. We image pH induced chemical changes on the curved and confined inner and outer surfaces of a cylindrical glass micro-capillary immersed in aqueous solution. The image contrast reports on the orientational order of interfacial water, induced by charge-dipole interactions between water molecules and surface charges. The images constitute surface potential maps. Spatially resolved surface pKa,s values are determined for the silica deprotonation reaction. Values range from 2.3
ISSN:2331-8422
DOI:10.48550/arxiv.1707.00590