An experimental determination of the absolute oscillator strengths of some resonance transitions of chromium and nickel

Abstract

A brief account is given of the classical electron theory of anomalous dispersion and line absorption. The oscillator strength, or f-value, is introduced as the factor involved in taking over the results of classical theory in a modern quantum mechanical formulation. The relation between f-values and the transition probabilities of Einstein is derived. A summary of methods for experimental determination of f-values for atomic transitions is given, and in particular the method of total absorption is considered in detail. The equivalent width or total absorption of an absorption line is defined, and the relation of this to the oscillator strength of the line, the so-called curve of growth, qualitatively explained. The laboratory apparatus used in the present investigation is described in detail, as are the methods of obtaining and reducing the experimental data. An account is given of unsuccessful experiments on the resonance lines of Ca. Absolute nf-values obtained for three lines of Cr are reported, and on the basis of unsatisfactory vapor pressure data, tentative absolute f-values for these lines are assigned. Absolute f-values for three lines of the Ni spectrum are reported, the vapor pressure data for Ni being reliable. A conversion factor is obtained by which the relative gf-values for Ni given by King may be reduced to an absolute scale.