Isotopic Displacement in Hyperfine Structure

Abstract

THE analysis of the hyperfine structure of several lines in thallium¹ indicates the existence of two distinct sets of energy levels, one for T1 203 and the other for T1 205. Each isotope has a nuclear spin i = ½. For the line 6s 7s ³S₁→6s 7p ¹P₁ in T1 II, the doublet width is approximately the same size for the two isotopes, which signifies that the magnetic moments must also be approximately equal. The distance between the centres of gravity of the two doublets, however, is greater for T1 205. Jackson,² studying rubidium, concludes that the lines are displaced toward the ultra-violet for the heavier isotope.