The Isotopic Constitution of Tungsten, Silicon, and Boron

Abstract

The isotopic constitutions of tungsten, silicon, and boron have been determined. Five isotopes of tungsten were observed at masses 180, 182, 183, 184, and 186 with abundances of 0.122 percent, 25.77 percent, 14.24 percent, 30.68 percent, and 29.17 percent, respectively. Three isotopes of silicon were observed at masses 28, 29, and 30 with abundances of 92.28 percent, 4.67 percent, and 3.05 percent, respectively. Two isotopes of boron were observed at masses 10 and 11 with abundances of 18.83 percent and 81.17 percent, respectively. Upper limits for the existence of other hypothetical normal isotopes in the immediate neighborhood of the known isotopes are given.