A study of absolute atomic transition probabilities; the correlation of oscillator strengths and vapor pressure

Abstract

A discussion of the absolute f-value of atomic transitions is given and the resulting relation between the equivalent width of an absorption line and the density is derived. This relation, referred to as the curve of growth, is examined in detail over a large range of the density factor; that is, for values beyond the linear region. Accurate computations are made for various values of the ratio of natural to Doppler broadening and tables presented in the appendices. An optical quartz cell was designed with a variable optical path length. This cell was used in conjunction with an electric furnace to construct the curve of growth entirely from the experimental data. The curves of growth were then correlated to the latest vapor pressure data yielding f-values for nineteen resonance lines of ten elements. The lines studied and the resulting f-values were Cu, λ3247 (0.322) and λ3274 (0.153); Ag, λ3281 (0.451) and λ3381 (0.175); Au, λ2676 (0.76); Zn, λ3076 (0.992 x 10^(-4)); Cd, λ3261 (2.05 x 10^(-3)); Ga, λ4033 (0.095); In, λ3039 (0.339) and λ4101 (0.172); Tl, λ2767 (0.219) and λ3775 (0.108); Sn, λ2863 (0.332), λ3009 (0.042), and λ3175 (0.065); and Pb, λ2833 (0.229), λ3639 (0.106), λ3683 (0.243), and λ4.057 (0.419). These results are correlated to those of other investigators and comments made on the connection between the f-value and the energy of the transition. For those elements which have a well-known f-value, the vapor pressure data are discussed. Corrections to the solar abundances are made on the basis of the results obtained.