Atomic spin precessions of fluorine ions recoiling through vacuum in weak transverse magnetic fields

Abstract

A new experimental method for unveiling the strong hyperfine interactions of multielectron ion configurations is described. It consists in observing atomic spin precessions of nuclear-excited ions recoiling through vacuum in weak external transverse magnetic fields. Due to the strong hyperfine coupling the nuclear orientation follows the atomic precession, resulting in a rotation of the angular correlation of decay v-rays. The method is illustrated using the long-lived 197keV t9F (5/2 +) state as probe. The observed large precessions as well as the strong attenuations of the 7-angular correlations are well accounted for by considering all possible configurations resulting from the coupling of L-shell electrons in the relevant ionic charge states.

Average charge state dependence in atomic spin precessions of fluorine ions emerging from iron and copper

“…The difference in precessions observed for fluorine ions on emergence from Fe (Z = 26) and Cu (Z = 29) is consistent with this observation. To compare experimental and theoretical data we regard only the dominant charge states 1 § 2 + and 3 + as emphasized in [3]. The mean charge state, however, accounts also for small contributions of the remaining charge states (essentially 0 § and 4+).…”

“…For the evaluation of the precession as well as for the attenuation coefficients two different approaches have been pursued yielding slightly different results. For a detailed description of these procedures and their discussion we refer to [3] (see Eqs. (13) and (19) of this reference).…”

“…For the calculation of the precessions we use average gvfactors correlated with averaged y-angular correlations for the different ion configurations (approach B in Ref. 3). Taking for Cu as fractions 18 ~, 48 and 27 ~o, respectively 1-7, 8-1, which correspond to an average charge state (compared to measured -166(4)mrad), assuming charge state fractions of 7 ~, 40 ~o and 40 ~o for the 1 § 2 + and 3 + ions, respectively.…”

“…The successful application of a new experimental method to the study of hyperfine interactions (HFI) in isolated ions has been reported recently [1][2][3]. With the isomeric 197 keV 19F state as probe it was demonstrated that the observed large rotations of the angular correlations of decay 7-rays are generated by atomic spin precessions of the ions when recoiling in vacuum through weak transverse magnetic fields.…”