Access Type

Open Access Dissertation

Date of Award

January 2011

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Physics and Astronomy

First Advisor

Peter M. Hoffmann

Abstract

At the nanoscale near an interface, the discrete nature of liquids is expected to influence various properties, such as density, viscosity or diffusion constants. Understanding interfacial properties of liquids is important for the development of nanotechnology, especially for the fields of nano-rheology and nano-tribology, and also for understanding various mechanisms in biological systems at the molecular level, such as protein folding or the self-assembly of lipid vesicles, which invariably involve liquids. Atomic force microscope (AFM) and fluorescence correlation spectroscope (FCS) are two complimentary techniques that are commonly employed investigate mechanics and dynamics of liquids at interfaces. In this thesis, the design and construction of a novel integrated platform combining AFM and FCS is presented. The platform consists of a newly built high sensitive AFM on top of an existing custom-made FCS setup. The design is modular in nature, can be easily assembled or disassembled and thus both AFM and FCS can be used independently. The successful operation was the platform was demonstrated by employing a colloidal liquid as a test system. Results of AFM experiments indicated the presence of structure to the colloidal dispersion under confinement, similar to the behavior of molecular liquids reported in the literature, at length scales of a few 10 nm. However, FCS results showed considerable decrease in the diffusion of colloidal particle even when the confinement was of the order of microns. The design, construction and the testing of the new platform along with the intriguing results will be presented.

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