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The isotopes of lithium, sodium, and potassium

1931; Elsevier BV; Volume: 212; Issue: 3 Linguagem: Inglês

10.1016/s0016-0032(31)90791-6

1879-2693

Kenneth T. Bainbridge,

Groundwater and Isotope Geochemistry

Part I. The relative abundance of the isotopes of lithium. Magnetic analysis of the positive rays of lithium from a heated spodumene source shows no change with temperature in the relative abundance of Li7 and Li6. This is in agreement with Aston and Morand but at variance with the results of G. P. Thomson, Dempster, and the similar work of Hundley. A possible explanation of Hundley's and Dempster's results appears when the effects of space charge and the geometry of the tube are considered. In the present work the ion currents were not limited by space charge, and the ions of the isotopes of lithium when brought successively to the receiving slit described exactly the same path throughout; the resolving power of the apparatus was great enough to secure complete separation of the ion beams, and proper diaphragming eliminated background due to strays. Part II. Positive Ion Sources. Ions of the alkali metals were produced from heated natural mineral silicates of the alkali metals. The technique of preparation and activation of these sources is described. The results of tests of the type and abundance of the emitted ions for five specific alkali metal ion sources are presented. Results are given of tests of barium and strontium positive ion sources. Part III. The Isotopes of Sodium and Potassium. Sodium and potassium have been examined for the presence of small amounts of isotopes other than Na23, and K39 and K41. If Na21 or Na25 exist at all they are present to less than 13000 of the main isotope and Na22 cannot be present to an extent greater than 1800 of Na23. From the analyses of potassium it is concluded that there is less than one part in 1500 of K43, less than one part in 600 of K42, and less than one part in 300 of K40, in reference to K39 if they exist at all. Part I. The Relative Abundance of the Isotopes of Lithium. A. Introduction. B. Conditions for determination of abundance ratios. C. Description of apparatus. a. Tube design. b. Ion source. D. Conditions for identical trajectories of ions of different e/m. E. Limitation of current by space charge. F. Measurement of ion currents. G. Method of procedure and results. H. Discussion of results. Part II. Digression on Positive Ion Sources. A. Ions of the alkali metals. B. Positive ions of barium and strontium. Part III. The Isotopes of Sodium and Potassium. A. Sodium. B. Potassium.