Experimentally measured oscillator strengths and associated radiative lifetimes of neutral vanadium using Fourier Transform Spectroscopy and Laser-Induced Fluorescence
File(s)
Author(s)
Holmes, Charlotte Emma
Type
Thesis
Abstract
Modern astrophysical analysis requires increasing higher resolution laboratory spectra over a broader spectral range. The advances in ground- and space-based telescopes are highlighting the deficiencies in the current laboratory spectral database. This thesis reports on the research carried out on the high resolution laboratory measurements of the spectrum of neutral vanadium and the associated lifetime measurements to calculate transition probabilities.
New measurements of radiative atomic lifetimes were made for 25 levels between 24648 cm−1 and 37518 cm−1 at the Lund Laser Center, Sweden, using the time resolved Laser-induced Fluorescence method.
High Resolution Fourier Transform (FT) Spectroscopy is used to observe the hollow cathode lamp spectrum of neutral vanadium in the range 2000 cm−1 - 35000 cm−1. This range was covered using two high resolution FT Spectrometers in Imperial College London and Lund University (Sweden) with a resolving power of approximately 2 million and 1 million respec- tively. This resolving power enables line profiles to be fully resolved to the Doppler width.
The high resolution spectra were used to measure the branching fractions of levels of interest which were then used in combination with the lifetime measurements to calculate the oscillator strengths. Across the UV, visible and IR spectral regions, radiative lifetimes and oscillator strengths for 208 lines between 3040 ̊A and 20000 ̊A from 39 upper energy levels are reported. 13 of these oscillator strengths have not been reported previously.
Additionally new measurements were made of hyperfine structure splitting factors for 3 odd levels of V I lying between 24700 cm−1 and 28400 cm−1.
New measurements of radiative atomic lifetimes were made for 25 levels between 24648 cm−1 and 37518 cm−1 at the Lund Laser Center, Sweden, using the time resolved Laser-induced Fluorescence method.
High Resolution Fourier Transform (FT) Spectroscopy is used to observe the hollow cathode lamp spectrum of neutral vanadium in the range 2000 cm−1 - 35000 cm−1. This range was covered using two high resolution FT Spectrometers in Imperial College London and Lund University (Sweden) with a resolving power of approximately 2 million and 1 million respec- tively. This resolving power enables line profiles to be fully resolved to the Doppler width.
The high resolution spectra were used to measure the branching fractions of levels of interest which were then used in combination with the lifetime measurements to calculate the oscillator strengths. Across the UV, visible and IR spectral regions, radiative lifetimes and oscillator strengths for 208 lines between 3040 ̊A and 20000 ̊A from 39 upper energy levels are reported. 13 of these oscillator strengths have not been reported previously.
Additionally new measurements were made of hyperfine structure splitting factors for 3 odd levels of V I lying between 24700 cm−1 and 28400 cm−1.
Version
Open Access
Date Issued
2015-12
Date Awarded
2016-07
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
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)