relation: http://d-scholarship-dev.library.pitt.edu/36725/
title: Surface Chemistry-Mediated Photoluminescence of Small Diameter Coinage Metal Nanoparticles
creator: Crawford, Scott
description: From size-dependent luminescence to localized surface plasmon resonances, the optical properties that emerge from materials with nanoscale dimensions have been revolutionary. As nanomaterials get smaller, they approach molecular electronic structures, and this transition from bulk to molecular electronic properties is a subject of far-reaching impact. One class of nanomaterials that exhibit particularly interesting optoelectronic features at this size transition are coinage metal (i.e., group 11 elements copper, silver, and gold) nanoparticles with core diameters between approximately 1 to 3 nm (∼25–200 atoms). Coinage metal nanoparticles can exhibit near-infrared photoluminescence features that are not seen in either their molecular or larger nanoscale counterparts. This emission has been exploited as a probe of electronic behavior at the nanoscale and in applications including biological imaging and sensing. Interestingly, photoluminescence figures of merit including quantum yield, energy, and lifetime are largely independent of particle diameter. Instead, coinage metal nanoparticle emission depends on particle surface chemistry, including both metallic composition and capping ligand architecture. The influence of surface chemistry on emergent optoelectronic phenomena has powerful implications for the study and use of these particles due to the theoretically limitless possible surface ligand architectures and metallic compositions.  This dissertation discusses the distinct roles of the ligand binding moiety and substituent structure, which are responsible for the “turn on” and fine-tuning of nanoparticle emission properties, respectively. Specifically, the use of ligand exchange strategies on non-luminescent phosphine-capped gold nanoparticles are used to contrast the impacts of strongly-binding (i.e. thiols and sulfides, Chapter 2), intermediate-binding (alkynes, Chapter 3) and weakly-binding (sulfoxides, Chapter 4) ligands on nanoparticle optoelectronic features.  The influence of core parameters on photoluminescence is then probed, including the number of valence electrons in the nanoparticle core (Chapter 5) and the metal composition (i.e. gold, silver, or copper, Chapter 6). This dissertation concludes by discussing how surface-mediated nanoparticle emission may be used for downstream applications, demonstrating efficient energy transfer from emissive gold nanoparticles to pendant ytterbium (Chapter 7). These materials are anticipated be foundational both in understanding the unique transition from molecular to bulk electronic structures and in the development of nanomaterials that leverage this transition.
date: 2019-09-26
type: University of Pittsburgh ETD
type: PeerReviewed
format: application/pdf
language: en
identifier: http://d-scholarship-dev.library.pitt.edu/36725/1/__PROD75-FS6.admin.netl.doe.gov_home_CRAWFORS_myfiles_Crawford_Scott_Dissertation.pdf
identifier:   Crawford, Scott  (2019) Surface Chemistry-Mediated Photoluminescence of Small Diameter Coinage Metal Nanoparticles.  Doctoral Dissertation, University of Pittsburgh.    (Unpublished)