The excitation potentials of the observed wavelengths of the spectral lines emitted in the low alloy steel spectrum were calculated. Tentative homologous line pairs were selected on the basis of similar excitation potentials and freedom from interferences. The slopes of the working curves were found to be independent of alloying elements, matrix, and discharge conditions. Alterations in the circuit parameters and consequent changes in the discharge had little or no influence upon the intercept of the working curves. Self-reversal of either or both of the alloying element line and the internal standard line was observed. The self-reversal was removed by selecting spectral lines of higher excitation potentials or directing an air blast across the discharge. In this way, the working curves were linear over all concentrations considered. Element interference correction factors, which were found to be functions of the concentration of the interfering element, could be applied to data so that one working curve could be used regardless of the major alloying constituents in the sample. Reproducibility tests indicate some improvement in accuracy when the air blast was employed.
J. K. HURWITZ and J. CONVEY, "Analysis of the Excitation Characteristics of Spectra Emitted by Ferrous Alloys," J. Opt. Soc. Am. 42, 24-27 (1952)