Chemistry, Department of
First Advisor
Xiao Cheng Zeng
Second Advisor
Barry Cheung
Third Advisor
Hui Li
Date of this Version
Summer 7-31-2020
Document Type
Article
Abstract
We report a joint anion photoelectron spectroscopy (PES) and theoretical study to investigate the effect of O2-binding on the mid-sized even-numbered gold clusters, Aun− (n = 20−34), a special size region of bare gold clusters that entail rich forms of structural evolution and transformation. Specifically, within this size range, bare Au20− is a highly-symmetric pyramidal cluster, bare Au21-25− are flat-planar or hollow-tubular clusters, bare Au26− is the smallest core-shell gold cluster, while bare Au34− is a magic-number/fluxional core-shell cluster with the high-symmetry tetrahedral Au4 core. In light of the strong size-dependent structural evolution of bare gold clusters in the n = 20−34 size range, we focused especially on the chemical interplay between the O2 binding and the structure of the host gold clusters. The global minima of the O2-bound gold clusters AunO2− are searched using the basin-hopping global optimization technique in conjugation with density functional theory calculations. Vertical detachment energies are computed for the low-lying isomers with the inclusion of spin−orbit effects for gold to generate simulated photoelectron spectra and to compare with the experimental PES spectra. Based on the global−minimum structures identified, a series of structural transitions, from the pyramidal to fused−planar to core-shell structures, are identified for the AunO2− clusters, where the O2 binding is found to be in either superoxo or peroxo fashion, depending on the size and shape of the host gold clusters.
Advisor: Xiao Cheng Zeng
Comments
A Thesis Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Chemistry, Under the Supervision of Professor Xiao Cheng Zeng. Lincoln, Nebraska: July, 2020
Copyright 2020 David Brunken-Deibert