Relative Sensitivities of Elements in a Spark-Source Mass Spectrograph

Abstract

Abstract The relative sensitivities of eleven elements in a spark-source mass spectrograph have been determined for monatomic singly-charged positive ions detected with Ilford Q2 plates. The results show that the elements have approximately the same sensitivities to within a factor of 3 in spite of large differences in both physical and chemical properties among them, and that the sensitivity of each element is constant in value within an uncertainty factor of 1.5, independent of changes in the bulk concentration of the element. Relative ion production rates have also been determined from the above sensitivities; they are in reasonable agreement with published values determined by electrical detection. From repeated measurements of the relative intensities of various ions, it has been suggested that relative ion yields from a spark ion source are not always constant for different elements. On the basis of these investigations, a discussion has been made of the general applicability of the sensitivity as the analytical constant in the quantitative mass spectrography of solids. Five different formulas have been used to express the “density” of mass lines, and exposures have been determined with an integrated monitor current. By trying several isotopic analyses, the calibration methods have been shown to be useful for mass spectrography.