From colloidal solution to single particles: investigating energy flow from semiconductor nanocrystals to molecules
Date
2021
Authors
Nilsson, Zach N., author
Sambur, Justin B., advisor
Barisas, B. George, committee member
Shores, Matthew P., committee member
Wilson, Jesse W., committee member
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Abstract
The interaction of nanomaterials and molecules is at the heart of many modern processes (catalysis, chemical synthesis, lighting, etc.). The presence of crystallographic defects in the nanomaterials can strongly influence this interaction or open up pathways for unintended interactions. The location of the defect sites plays a large role in determining how a defect sites will interact with the environment around it. Determining the location of defect sites in nanomaterials is a challenge. Transmission electron microscopy (TEM) is the obvious choice to observe atomic scale defects however, in situ TEM measurements are difficult and expensive. Forster resonance energy transfer (FRET) spectroscopy has the power to reveal nanoscale distances from optical data. FRET has been applied to nanomaterial defects in the past but never to reveal the location of defect sites. The following work describes the application of FRET spectroscopy to an ensemble of zinc oxide nanoparticles. It was found that for large nanoparticles (6 nm diameter) FRET could distinguish between surface and interior defect sites. However, the ensemble level approach has limitations. To overcome these, the system was observed on the single particle level using optical microscopy. Single particle studies revealed that energy transfer events appear to be very rare in this system. No conclusive evidence of energy transfer was observed on the single particle level.
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Subject
energy transfer
nanomaterial
defect
zinc oxide
FRET