UBC Theses and Dissertations
Measurement of relative transition probabilities in argon using the Faraday effect Stockmayer, Philip Henry
Relative transition probabilities for some spectral lines connecting the 4s and 4p states of neutral argon have been determined by a relatively new technique developed by Seka and Curzon involving the Faraday effect. In this method a given spectral line emitted by an argon discharge tube is plane polarized and then passed through an absorption tube embedded in an axial magnetic field. The rotation of the plane of polarization, and the intensity of the source line are measured and from the results the absorption coefficient for that particular line in the plasma is deduced. The theory used agrees excellently with the observed rotations for field values from 0 to 2600 gauss. This technique is particularly suited to strong transitions which are difficult to measure by other methods. The values obtained here for the transition probabilities are quite accurate (errors < 10%) and agree well with values given by Weise in a recent compilation. For the analysis of the Faraday rotation it was necessary to determine the effect of the magnetic field on the number density of lower excited states in the absorbing plasma. This was done using a relative absorption technique, the results of which show a linear decrease in the number densities in the first 2000 gauss.
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