Abstract
A mass spectrometric study has been made of the influence of the filament temperature on ion production, the ratio of oxide ion(MO+)to element ion(M+)and the relative ionization efficiency of rare earth elements. From the present experimental results, it has been found that:(1)In the triple-filament method, light rare earths(from La to Eu)are generally ionized at lower side-filament temperatures than are heavy rare earths(from Gd to Lu). Exceptionally Eu and Yb are ionized at the lowest side-filament temperature in light and heavy rare earths, respectively. (2)In both triple-and single-filament methods, the ratio of oxide ion to element ion decreases with the increase in the atomic number of light rare earths. Heavy rare earths also show the same tendency. In triple filament method this ratio is not largely changed by the side-filament temperature, though it is sharply dependent on the vacuum of the ion source. (3)In the triple filament method, the ionization efficiency of light rare earths is larger than that of heavy rare earths by about one order.
