Hyperfine structure anomaly and magnetic moments of neutron deficient Tl isomers withI=9/2

Abstract

The hyperfine structure of 276.9-nm atomic transition has been studied by the resonant ionization spectroscopy method at mass-separator IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron), Petersburg Nuclear Physics Institute (PNPI) for the odd Tl isomers with $I$ = 9/2 and $A$ = 187--197. A differential hyperfine structure anomaly for $6p{}^{\phantom{\rule{0.16em}{0ex}}2\phantom{\rule{-0.16em}{0ex}}}{P}_{1/2}$ and $7s{}^{\phantom{\rule{0.16em}{0ex}}2\phantom{\rule{-0.16em}{0ex}}}{S}_{1/2}$atomic states in Tl isomers with $I$ = 9/2 has been determined. It is described by the recently developed theoretical approach fairly well. This enables one to recalculate the magnetic moments of ${}^{187\ensuremath{-}193}$Tl${}^{m}$ ($I$ = 9/2) from previously measured hyperfine splittings for $7s{}^{\phantom{\rule{0.16em}{0ex}}2\phantom{\rule{-0.16em}{0ex}}}{S}_{1/2}$ states and to determine for the first time the magnetic moments for ${}^{197}$Tl${}^{m}$ and ${}^{195}$Tl${}^{m}$ ($I$ = 9/2) from hyperfine splittings for $6p{}^{\phantom{\rule{0.16em}{0ex}}2\phantom{\rule{-0.16em}{0ex}}}{P}_{1/2}$ states with properly taking into account the rather great hyperfine structure anomaly. Similar measurements with greater accuracy have been proposed for the other nuclear states in odd-odd Tl isotopes. These measurements could shed light on the nuclear magnetization distribution in these isotopes.