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UBC Theses and Dissertations

Method to measure line shapes and relative transition probabilities Camm, David Malcolm


An accurate method to measure line shapes and relative transition probabilities between transitions with a common lower state has been developed. Argon was used as a test gas to show that this method is more accurate than other current procedures. The experimental observations agree well with the theory developed in this thesis. It is shown that the ratio of the Lorentzian to Doppler half-widths of the line can be measured to a precision of 10% when the Doppler width is as much as one hundred times larger than the Lorentzian half-width. The relative transition probabilities can be measured to within 10% for weak lines and to 1 % for strongly absorbing lines. The line shapes measured are consistent with those predicted by Griem (2) and the relative transition probabilities agree well with the values given by Wiese (5). This absorption experiment uses a glow discharge for the source and absorber. The absorption tube is placed between Nicol prisms and a longitudinal magnetic field is applied to Zeeman split the absorption lines. The transmission as a function of field depends on both the transition probabilities and the line shape of the absorption lines. The high resolving power required to measure the line shapes is obtained from the Zeeman splitting of the absorption lines rather than a spectrometer. The method is an inexpensive, accurate way to measure line shapes and relative transition probabilities especially suited for strongly absorbing lines.

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