Isotope Effect on Bond Rupture by Electron Impact on Hydrogen, Deuterium, and Tritium

Abstract

The relative yields by electron impact of atomic and molecular ions, x⁺/x₂⁺ ratios, from hydrogen, deuterium, and tritium have been measured with a 60° sector type mass spectrometer. It is shown that the major part of the previous disagreement between calculated and observed values can be understood on the basis of voltage discrimination by the ion source. By using magnetic scanning and a high ion accelerating voltage the experimental ratios are: H⁺/H₂⁺=0.013, D⁺/D₂⁺=0.0070, T⁺/T₂⁺=0.0036 for 30 volt electrons. These are to be compared with the calculated ratios: H⁺/H₂⁺=0.016, D⁺/D₂⁺=0.0072, T⁺/T₂⁺=0.0038.