J dependence of the isotope shift in the ground term of dysprosium I

Abstract

High-resolution laser-atomic-beam measurements have been made to study the J dependence in the optical isotope shift of the ground term 4f/10 6s2 5I of the naturally occurring dysprosium isotopes 160, 161, 162, 163, and 164. For each isotope pair with mass numbers A and A′, this J dependence is described through one parameter z4fAA′, whose angular coefficient for a level is equal to that of the spin-orbit radial integral ζ4f. The J dependence can be explained by field-shift-crossed second-order effects.