SPECTROSCOPIC APPLICATIONS OF THE PLASMA DISPERSION FUNCTION

Using as a starting point a previously published approximate expressio n for the spectroscopic absorption Voigt profile, an absorption-disper sion pair for mildly Gaussian lines is constructed. With this informat ion, the full asymptotic expansion of the plasma dispersion function ( PDF) is obtained for the case of Im z > 0. As shapes and widths of spe ctral lines contain much information about the phenomena accompanying the resonance, it is suggested that the PDF may be of interest in spec troscopy for the study of Voigtian line structure, Because many lines in spectroscopy are asymmetrical, a generalization of the absorption a nd dispersion profiles for mildly Gaussian lines is done by introducin g an asymmetry factor. Finally, an application example to test the ade quacy of the line model proposed here is given. To this end, a neutral helium line emitted from an electron cyclotron resonance microwave pl asma is chosen as the subject of the test, to estimate the temperature of the neutral component of the plasma. The results are consistent wi th those of similar experiments reported in the literature which might show the usefulness of the line model proposed in this work.