Measurement of Relative gf-Values and Collisional Damping Constants for Spectral Lines of Neutral Calcium

Citation

Olsen, Kenneth Harold (1957) Measurement of Relative gf-Values and Collisional Damping Constants for Spectral Lines of Neutral Calcium. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2584-MH64. https://resolver.caltech.edu/CaltechETD:etd-07152004-143851

Abstract

The relative gf-values for 107 lines in 34 multiplets of Ca I between [lambda] 2990 and [lambda] 6720 have been derived from the photographic photometry of absorption lines excited in an electric furnace. All the lines arise from low terms whose excitation potentials range from 0.0 to 3.0 e.v. A brief discussion of the method used for making the measurements is given, together with an outline of the theoretical relationships which are required to reduce the measurements to relative gf-values. The various components of the experimental apparatus are described in some detail. In the second part, some preliminary studies have been made on the pressure broadening of Fe I and Ca I absorption lines in electric furnace spectrograms. By using relative gf-values for lines of these elements, empirical curves of growth have been constructed from which the collisional damping constants for some of the lines are derived. The experimental damping constants are compared with those calculated from the available theories of pressure broadening. The results indicate that observations of broadened absorption lines in furnace spectra may prove useful in determining collisional damping constants for many lines of astrophysical interest.

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