Conduction Electron Spin Resonance of Small Metallic Nanoparticles
Open Access
- Author:
- Cruz, Santina
- Graduate Program:
- Chemistry (PHD)
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- October 05, 2021
- Committee Members:
- Thomas Mallouk, Committee Member & Major Field Represnt
Raymond Schaak, Committee Member & Major Field Represnt
John Golbeck, Committee Member & Related Areas Repres
Philip Bevilacqua, Program Head/Chair
Benjamin Lear, Chair & Dissertation Advisor - Keywords:
- metallic nanoparticles
electron spin resonance
nuclear magnetic resonance
magnetic susceptibility
plasmon
morphology
ligands
electron paramagnetic resonance
Evans Method
conduction electron spin resonance
surface chemistry
solvent
electronic properties - Abstract:
- Metal nanoparticles (NPs) have demonstrated value across many fields of research, including plasmonic solar cells, heterogeneous catalysis, as well as diagnostics and therapeutics. In each of these applications, the NPs’ metal core offers unique electronic properties not observed in the bulk material. This is, in part, due to the increase in surface area to volume ratio as the size of the NP decreases. It is well established that the electronic properties of metal NPs can be tuned by modifying the size, shape, and dielectric environment of the particle. However, although chemical reasoning suggests that the surface plays an equally important role, much less is known about how precise modifications to the surface chemistry impact the metal core properties. In this work, two magnetic resonance techniques, conduction electron spin resonance (CESR) spectroscopy and the Evans nuclear magnetic resonance (NMR) method, are employed to study the effect that the ligand shell, particle morphology, and dispersing solvent have on the electronic structure of noble metal NPs. Herein, we have also utilized CESR to demonstrate that the morphological asymmetry of dodecanethiolate protected noble metal NPs (Cu, Ag, Pd, Ir, Pt, and Au) gives rise to asymmetries in the electronic behavior. Furthermore, a new synthetic method for < 10 nm alkanethiolate protected silver NPs has been developed. Using these particles, an interesting connection between CESR and NMR suggests that the Fermi level (EF ) moves through the band structure. Finally, in corroboration with previous findings, we demonstrate that the solvent influences the electronic behaviors of silver nanoparticles. In total, this work suggests that the surface chemistry is a vital means in controlling the electronic properties of small metallic nanoparticles.