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Theses Doctoral

Interactions between 0-Dimensional and 2-Dimensional Materials

Chen, Zheyuan

This thesis describes two types of interactions between zero-dimensional and two-dimensional materials: energy transfer and surface diffusion. The first chapter introduces zero-dimensional and two-dimensional materials and their unique properties. Based on emerging properties different from bulk materials', several attempts have been shown to study the interaction between these two classes of materials. The second chapter presents the study on the energy transfer between zero-dimensional and two-dimensional materials, specifically semiconductor nanocrystals (or "quantum dots") and graphene. The fluorescence quenching was observed for quantum dots on graphene compared those in the absence of graphene. The strong energy transfer is through Coulomb interaction in the way similar to Forster resonant energy transfer. Based on simple assumptions, energy transfer between quantum dots and single-layer graphene was extended to quantum dots and few-layer graphene and quantitative agreement was achieved between experimental results and calculation from theory. The third chapter investigates the surface diffusion of zero-dimensional materials on a two-dimensional material. Metal adatoms diffuse on graphene and form different nanostructures depending on the supporting substrate for graphene. As a atomically thin material, graphene is susceptible to change in underlying supporting substrates. This susceptibility will introduce surface corrugation, chemical reactivity and electron-hole puddles to graphene, and finally will lead to different morphology of metal nanoparticles on graphene. Using classical nucleation theory, different diffusion constants of Au adatoms were reported on graphene supported by different substrate. Two major factors are identified to explain the difference: surface corrugation and π electronic stabilization. In the final chapter, the characterization of zero-dimensional and two-dimensional materials is discussed. It is mainly done using Raman spectroscopy, which is a non-destructive tool. Without knowing the pristine properties of materials, their interactions with other materials are beyond reach.

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More About This Work

Academic Units
Chemical Physics
Thesis Advisors
Brus, Louis E.
Degree
Ph.D., Columbia University
Published Here
August 22, 2011
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