The spectrum and term analysis of doubly-ionised iron
File(s)
Author(s)
Concepcion Mairey, Florence
Type
Thesis
Abstract
The study of astrophysical spectra is reliant on accurate atomic data, and there is a need for the atomic data of iron as its spectral lines are present and numerous in many astrophysical sources, due to its high relative abundance and complex spectrum.
This PhD thesis reports the results of the term analysis of doubly-ionised iron (Fe III). A Penning discharge lamp is used to generate the spectrum of Fe III, which is recorded using the Fourier transform spectrometer (FTS) at Imperial College London, UK. The FTS recorded high-resolution Fe III lines in the UV range of 33,826 cm⁻¹ to 65,508 cm⁻¹. This was supplemented with grating spectral data at high wavenumbers (55,090 cm⁻¹ to 111,121 cm⁻¹) from the normal incidence vacuum spectrograph at the National Institute of Standards and Technology in Maryland, USA. The linelists created from the FTS and grating data were wavenumber calibrated using the accurate Fe II Ritz wavelengths produced by Nave & Johansson (2013) [1]. FTS line wavenumbers were calibrated to an accuracy of 5 − 8.5 parts per 10⁸, depending on the spectrum, with uncertainties of strong lines typically between 0.0024 cm⁻¹ and 0.0074 cm⁻¹. The uncertainties of the grating lines are between 0.091 cm⁻¹ and 0.86 cm⁻¹.
The classified spectral lines are used in the term analysis to revise 305 Fe III energy level values in configurations 3d⁶, 3d⁵4s, 3d⁵4p, 3d⁵4d, 3d⁵5s, and 3d⁵5d. The Ritz wavenumbers of 1599 classified Fe III lines were calculated, providing wavenumbers at least an order of magnitude more accurate than previously published linelists. The Ritz wavenumbers for 432 parity-forbidden lines were also calculated. The results of this thesis will be used by astronomers for the identification and analysis of Fe III spectral lines in astrophysical spectra.
This PhD thesis reports the results of the term analysis of doubly-ionised iron (Fe III). A Penning discharge lamp is used to generate the spectrum of Fe III, which is recorded using the Fourier transform spectrometer (FTS) at Imperial College London, UK. The FTS recorded high-resolution Fe III lines in the UV range of 33,826 cm⁻¹ to 65,508 cm⁻¹. This was supplemented with grating spectral data at high wavenumbers (55,090 cm⁻¹ to 111,121 cm⁻¹) from the normal incidence vacuum spectrograph at the National Institute of Standards and Technology in Maryland, USA. The linelists created from the FTS and grating data were wavenumber calibrated using the accurate Fe II Ritz wavelengths produced by Nave & Johansson (2013) [1]. FTS line wavenumbers were calibrated to an accuracy of 5 − 8.5 parts per 10⁸, depending on the spectrum, with uncertainties of strong lines typically between 0.0024 cm⁻¹ and 0.0074 cm⁻¹. The uncertainties of the grating lines are between 0.091 cm⁻¹ and 0.86 cm⁻¹.
The classified spectral lines are used in the term analysis to revise 305 Fe III energy level values in configurations 3d⁶, 3d⁵4s, 3d⁵4p, 3d⁵4d, 3d⁵5s, and 3d⁵5d. The Ritz wavenumbers of 1599 classified Fe III lines were calculated, providing wavenumbers at least an order of magnitude more accurate than previously published linelists. The Ritz wavenumbers for 432 parity-forbidden lines were also calculated. The results of this thesis will be used by astronomers for the identification and analysis of Fe III spectral lines in astrophysical spectra.
Version
Open Access
Date Issued
2022-03
Date Awarded
2022-11
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Pickering, Juliet
Sponsor
Science and Technology Facilities Council (Great Britain
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)