Solid-state NMR analysis of the surfaces and interfaces in nanoscale materials.

摘要

Semiconductor nanocrystals, with unique size-dependent properties, give promise for successful innovation of new technologies including solid-state lighting and biological labeling. Therefore, characterization of the surfaces, interfaces and associated reconstruction in these materials becomes crucial for an understanding of structure-function relationships essential to this development. In this dissertation, powerful solid-state nuclear magnetic resonance (NMR) techniques, such as cross-polarization magic angle spinning (CPMAS), spin-echo, and two dimensional (2D) heteronuclear chemical shift correlation (HETCOR) experiments are utilized to probe these various regions in CdSe and InGaP nanocrystals. These experiments reveal fundamental structural information, including insight into atomic vacancies, discrete particle reconstruction with size, oxidation, passivation, and the nature and molecular order of the surface, near surface and core species. This knowledge gives rise to valuable direct correlations of the structural molecular models of reconstruction with the physical properties of CdSe and InGaP nanomaterials.