Electronic Structure of Metal-Containing Diatomic Ions Pubblico
VanGundy, Robert (Fall 2018)
Published
Abstract
Investigation of eight neutral molecules and their ions, SmO, NdO, ThCl, UN, BaO, BaCl, CaO, and CaOH+ using gas phase spectroscopy will be described. These molecules have been studied using a combination of the following spectroscopic techniques: laser-induced fluorescence (LIF), dispersed fluorescene (DF), resonant multiphoton ionization (REMPI), photoionization efficiency (PIE), pulsed-field ionization zero kinetic energy (PFI-ZEKE) photoelectron spectroscopy.
Previous literature values suggests the chemi-ionization reaction proceeds spontaneously for both samarium and neodymium. In an effort to increase electron density in the ionosphere Air Force Research Laboratory (AFRL) is interested in test releases of both samarium and neodymium. Following samarium releases, the magnitude of electron density created was two orders of magnitude lower than expected. A reevaluation of the thermochemical data was performed. Determination of the ionization energy of SmO contributed to understanding the samarium chemi-ionization reaction, and the lower observed electron density. A proactive reevaluation of the neodymium thermochemical data was performed to advise AFRL on the suitability of Nd test releases. Determination of the ionization energy of NdO contributes to the suggestion that Nd is a good candidate for these test. The low-lying transition of NdO+ are also reported.
The first gas-phase spectroscopic studies on ThCl, ThCl+, and UN+ identify constants for the ground state, as well as term energies for low-lying excited electronic states. Theoretical treatment of actinides is difficult and experimental observation of predicted transitions provides an indication of the accuracy of current high-level computational methods, as well as a benchmark for further development of theoretical models.
Alkaline-earth ions are isoelectronic to the alkali metals. Therefore, well-studied laser cooling schemes to create ultracold alkali atoms can be adjusted for these alkaline-earth ions. The electric charge allows for trapping via rf fields and further experimentation. These atoms are trapped in a coulomb crystal and molecular ions can be created in these traps by addition of a reactant gas. Knowledge of the ionic transitions of these created molecules is necessary to determine the temperature of these molecules. The low-lying states of BaO+, BaCl+, and CaO+ are reported, and compared to current theoretical treatments. Attempts to investigate CaOH+ as well as miscellaneous laboratory contributions are also described.
Table of Contents
Chapter 1.1. Introduction 1
1.2. References 5
Chapter 2. Evaluation of the Exothermicity of the Chemi-ionization Reaction 7
Sm + O → SmO+ + e-
2.1. Introduction 7
2.2. Experimental and Theoretical Methods 11
2.2.1. SIFT Apparatus 11
2.2.2. Guided Ion Beam Tandem Mass Spectrometer 12
2.2.3. GIBMS Data Analysis 14
2.2.4. REMPI and PFI-ZEKE 15
2.3. Experimental Results 16
2.3.1. SIFT 16
2.3.2. GIBMS 18
2.3.2.1. Sm+ + LO (L = O, SO, C) 18
2.3.2.2. SmO+ + Xe/O2 22
2.3.3. REMPI and PFI-ZEKE 22
2.4. Thermochemical Results 25
2.4.1. SmO+ 25
2.4.2. Other Thermochemical Results 27
2.5. Discussion 28
2.5.1. Chemi-Ionization Reaction 28
2.6. Conclusion 30
2.7. References 31
Chapter 3. Probing the Electronic Structure of NdO+ 49
3.1. Introduction 49
3.2. Experimental Details 51
3.3. Results and Discussion 53
3.4. Conclusion 56
3.5. References 58
Chapter 4. Spectroscopic and Theoretical Studies of ThCl and ThCl+ 65
4.1. Introduction 65
4.2. Computational Treatment of Ground and Lowy-Lying Excited 67
States of ThCl and ThCl+
4.3. Experiment 71
4.4. Experimental Results and Analyses 73
4.5. Discussion 76
4.6 Conclusion 79
4.7. References 81
Chapter 5. Spectroscopy of the Low-Lying States of UN+ 93
5.1. Introduction 93
5.2. Experiment 95
5.3. Results 96
5.4. Analysis and Discussion 98
5.5. Conclusion 101
5.6. References 102
Chapter 6. Spectroscopy and Theoretical Studies of the Low-Lying States of BaO+ 109
6.1. Introduction 109
6.2. Experimental 111
6.3. Results 112
6.4. Electronic Structure Calculations 114
6.5. Data Analysis 117
6.6. Discussion 118
6.7. References 122
Chapter 7. Characterization of the BaCl+(X1Σ+) Cation by Photoelectron Spectroscopy 136
7.1. Introduction 136
7.2. Experimental 137
7.3. Results and Discussion 138
7.4. References 141
Chapter 8. Spectroscopy of the Low-Lying States of CaO+ 147
8.1. Introduction 147
8.2. Experimental 149
8.3. Results 150
8.4. References 156
Chapter 9. Miscellaneous and Uncompleted 165
9.1. Introduction 165
9.2. Experimental Details and Results for CaOH+ 166
9.3. Continuum ND6000 Repair 167
9.4. Source Motor Redesign and Wiring 168
9.5. References 171
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