Transport of Material in Sources for Spectroscopic Analysis

Abstract

A study of the transport of material in the condensed d-c. spark discharge has been made, with the object of placing quantitative spectroscopic methods of analysis on a less empirical basis and thus permitting, (a) the recognition of certain conditions of source operation which lead to unreliable determinations, and (b) the determination of some of the criteria to be fulfilled for maximum precision in analytic measurements.Variations in the transport phenomena, as indicated by variations in the relative distributions of emitting atoms of various elements along the discharge axis on the addition of certain substances to a sample, appear to be closely connected with the ionization potentials and masses of the elements, and with the ionization potentials of other particles present in the discharge. The data indicate the necessity for the use of a spectroscopic buffer, and provide certain criteria for the choice of the buffer and of the internal standard element.The exact nature of the mechanism of transport is uncertain, but various considerations indicate that neither the motion of ions under the influence of the field nor diffusion in the ordinary sense is sufficient to account for observed features.

Analysis of Organic Materials for Traces of Metallic Impurities

“…The primary requirements for such a buffer are that it contain none of the test elements, either as a constituent or an impurity; that it contain a metal of sufficiently low excitation potential to maintain an arc of constant spectral character, regardless of the sample composition; and that it volatilize at a uniform rate during the entire arcing period. The buffers tried were selected upon the basis of previous work in this and other laboratories (6,8,11).…”