Effects of Source Parameters on the Ion Intensity in a Triggered DC Spark Source Mass Spectrograph

Abstract

A study was made of the influences of source parameters on ion intensities of various elements in a triggered DC spark source mass spectrometry, in order to apply the mass spectrometric method to the analysis of iron and steel. The experiment was carried out with a CEC#21-11OB type doublefocusing mass spectrograph equipped with a triggered DC spark source system. The source parameters observed are a sustain voltage(0∼800V), a triggered voltage(0∼3000V), a pulse length(0∼10μsec), a sustain capacitance(0.5∼20μF)and a frequency(10∼3000c/s). A sustain voltage is remarkably effective and ion intensities are abruptly varied in the voltage range between 400 and 600V, especially in an iron matrix sample. Generally, it was found that the amount of M2+ produced with this spark source system is greater than that produced with a R. F. spark source. The behavior of each element can be divided into two general classes: V, Cr, Mo and Nb are belong to one class, and As, Ga and Ag the other, whose characteristics depend on the second ionization potential of each element. Ion intensities are not varied by change of source parameters except a sustain voltage. A frequency is suitable as a variable parameter for regulating ion intensities. At the sustain voltage of 300V, the intensity ratio of M+/M2+ increases considerably in comparison with at that of 600V. Darkening curve gets out of parallel shape under a different source condition. Reproducibilities, on the whole, are 3∼30%for coefficients of variation which agree with those in the R. F. spark source system.