Date of Award
1993
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
High resolution photoelectron spectra of numerous Group IV, VII and VIII compounds have been recorded using a newly constructed photoelectron spectrometer based on the McPherson ESCA 36 hemispherical analyzer. This spectrometer is designed to make use of the high electron resolution and transmission of the analyzer coupled with the tunability and high photon resolution which is inherent in synchrotron radiation.;For the first time using this instrument, it has become possible to differentiate between three distinct core level broadening mechanisms: vibrational and ligand field splitting and a chemical effect on linewidths. Several I 4d photoelectron spectra of seven different iodine-containing compounds are reported. Ligand field splitting (as measured by the asymmetric C{dollar}\sbsp{lcub}2{rcub}{lcub}0{rcub}{dollar} crystal field term) is shown to split the 4{dollar}d\sb{lcub}3/2{rcub}{dollar} and 4{dollar}d\sb{lcub}5/2{rcub}{dollar} into a doublet and triplet, respectively. The C{dollar}\sbsp{lcub}2{rcub}{lcub}0{rcub}{dollar} values, like the binding energies, E{dollar}\sb{lcub}\rm 4d{rcub}{dollar}, generally increase as the ligand electronegativity increases and correlate well with the nuclear field gradient, eq{dollar}\sb{lcub}\rm n{rcub}{dollar}. For the first time, I show that the I 4d linewidths generally decrease as the electronegativity of the ligand increases, and as the valence I 5p electron density decreases.;Ligand field splitting has also been resolved on the Xe 4d spectra of the xenon fluorides. The spectra of XeF{dollar}\sb2{dollar} and XeF{dollar}\sb4{dollar} are very similar to the spectra of ICl, IBr and HI. In the case of XeF{dollar}\sb6{dollar}, an asymmetry is observed on the high binding energy side of the Xe 4{dollar}d\sb{lcub}3/2{rcub}{dollar} band. This is attributed to an appreciable ligand field splitting showing that XeF{dollar}\sb6{dollar} is distorted from octahedral symmetry. I derive the bond angles for the C{dollar}\sb{lcub}3v{rcub}{dollar} XeF{dollar}\sb6{dollar} structure using the C{dollar}\sbsp{lcub}2{rcub}{lcub}0{rcub}{dollar} for XeF{dollar}\sb6{dollar} and a partial ligand field splitting model, which gives estimates of {dollar}\Theta\sb{lcub}1,2,3{rcub}{dollar} = 50 {dollar}\pm{dollar} 2{dollar}\sp0{dollar} and {dollar}\Theta\sb{lcub}4,5,6{rcub} = 76 \pm 4\sp0{dollar}.;High resolution spectra of the Ge 3d and Sn 4d levels of several compounds are reported. The spectra of GeH{dollar}\sb4{dollar} and AsH{dollar}\sb3{dollar} demonstrate that the observed vibrational intensity is related to the metal's position on the Periodic Table. The spectra of GeF{dollar}\sb4{dollar} and SnCl{dollar}\sb4{dollar} prove that orbital interaction is possible between atomic levels thereby creating pseudo-bonding orbitals.;The valence band spectra of XeF{dollar}\sb4{dollar} and XeF{dollar}\sb6{dollar} are recorded as a function of incident photon energy. Valence band branching ratios were obtained from 21 to 100 eV photon energy. Theoretical branching ratios and partial cross-sections were obtained from MS-X{dollar}\alpha{dollar} calculations and are compared to experimental results. In general, good agreement was found between theory and experiment.
Recommended Citation
Cutler, Jeffrey N., "High-resolution Photoelectron Spectroscopy Using Synchrotron Radiation: Ligand Field And Vibrational Splitting And Chemical Effects On Linewidths" (1993). Digitized Theses. 2210.
https://ir.lib.uwo.ca/digitizedtheses/2210