Abstract
An ion source to get an ion beam of oxygen was constructed. A stable ion beam of oxygen was obtained. The current and the diameter of the beam were 1.2×10-7 A and 100μm, respectively. The ion source was attached to a secondary ion mass spectrometer as the primary ion source. The preliminary measurements of the isotopic ratios of chromium, iron, and nickel were performed for the sample of stainless steel. The relative sensitivities of Ti, V, Cr, Mn, Co, and Ni to Fe were obtained by the use of the standard sample of low alloy steel(NBS, No. 466). The results were compared with those obtained by the primary ions of argon. It was found that the differences of the relative sensitivities among these elements were small for oxygen primaries compared with that for argon primaries.
