Relative Measurements of Lithium Isotope Ratio by Surface Ionization Source I. Laboratory Standard Lithium Sulfate(Merck)

Abstract

Relative measurements of lithium isotope ratio for lithium sulfate(Merck)have been made by using a surface ionization ion source of the triple filament type. The isotope ratio obtained by the measured point method is(⁷Li/⁶Li)M.P=12.38±0.03 and fairly coincides with the isotope ratio(⁷Li/⁶Li)I.I=12.39±0.01 by the ion current integration method.The distribution of the isotope ratios obtained by the measured point method with time is normal. The measurable isotope fractionation over the lifetime of sample evaporation is not found. The background ions emitted from the tungsten filament are also examined and their behaviours are discussed.