Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Physics and Astronomy

Committee Chair/Advisor

Joan Marler

Committee Member

Endre Takacs

Committee Member

Bradley Meyer

Committee Member

Jonathan Zrake


Analysis of astrophysical phenomena requires an understanding of the electronic

structure and transition probabilities of the elements present in that environment,

yet there are still many charge states of heavy elements whose electronic

structures and spectroscopic properties are not yet well understood. To address this,

we investigated the spectroscopic properties of three different elements through an

analysis of spectra collected from three different experimental apparatuses.

In order to better understand the spectroscopic properties of Ni I and II, we

analyzed spectra collected from the Compact Toroidal Hybrid (CTH) apparatus at

Auburn University. In this experiment, a nickel sample was inserted into the CTH

plasma, where nickel atoms where ablated and then excited by a pulsed plasma.

Emitted photons are collected by a UV/VIS spectrometer for analysis. The wavelength

range studied in this experiment was 200nm to 800 nm. Nickel peaks in the

resulting spectra were identified by looking at the dependence of peak intensity upon

the depth of the sample into the plasma, as well as by comparing to spectra collected

using a gold sample in the CTH. In this experiment, 130 previously reported nickel

lines were observed as well as 18 lines that, to the best of our knowledge, have not

been previously observed. Additionally, 19 previously observed Ni II emission lines

were confirmed and one new emission line was identified which was not previously

observed. These previously unobserved lines were identified by using known energy levels from the National Institute of Technology (NIST) Atomic Spectral Database

(ASD) to calculate the Ritz wavelength of electric dipole-allowed transitions. We

also present preliminary benchmarks of recent Ni II R-matrix calculations using our

experimentally observed lines.

Using the results of the above, we then conducted the first analysis of nickel

and iron emission lines in comet Hyakutake. Our experimental spectra, along with

previously published emission lines of nickel and iron, and a fluorescence model that

calculates the predicted emission of nickel and iron in the comet coma, were used to

identify emission lines present in the comet and analyze the line intensities to estimate

abundances of nickel and iron. These abundances and their spatial distributions

within the comet’s coma were then used to analyze which parent molecules in the

comet could have led to gaseous nickel and iron in the coma.

Our spectral analyses were extended beyond nickel by analyzing the emission

between 200 and 1500nm of Ir I and II lines from a hollow cathode lamp (HCL). The

aim of this project was to identify previously unobserved emission lines of Ir as well

as to analyze how the observed lines change with electron temperature. These results

could also be used to inform future studies of Ir in the CTH. Because the HCL is

filled with a neon buffer gas, the collected spectra only contains significant emission

from Ir and Ne, making the spectra cleaner and easier to identify lines. Additionally,

the steady state nature of the HCL allowed us to use longer exposure times than

those used in the CTH, making it possible to observe weak emission lines. Although

this analysis is not yet complete, significant progress has been made to analyze the

spectra and identify observed Ir I and II lines.

A third apparatus, the electron beam ion trap (EBIT) facility at the National

Institute of Standards and Technology (NIST), was used study highly charged Pr.

An EBIT, which traps and ionizes atoms via electron impact ionization, allows one to observe different high charge states by varying the electron beam energy. For this

study, the NIST EBIT produced Pr25+ through Pr33+ and their emitted spectra was

observed. The EBIT was run with varying electron beam energies, and the light

emitted between 8nm and 25.5nm was collected by a spectrometer. These spectra

were then compared to theoretical spectra produced using the Flexible Atomic Code

(FAC) as well as the NOMAD collisional-radiative model, and the change in line

intensity with respect to electron beam energy was analyzed in order to identify Pr

emission lines.



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