Hyperfine fields at theFe57nucleus in monovalent iron (D6, 3d64s) isolated in solid xenon

Abstract

The Mössbauer effect was used to unequivocably identify and measure the effective internal magnetic field at the ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ nucleus in monovalent iron in its ${}_{}{}^6{}_{}{}^{}D$, $3d^{6}4s$ state isolated in a xenon matrix. The monovalent iron was produced by depositing the iron atoms in a matrix doped with HI and the subsequent electron transfer between the electron donor (${\mathrm{Fe}}^0$) and the acceptor species promoted by photoexcitation. For an applied external field of 28 KOe, an induced anisotropic magnetic hyperfine field at the ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ nucleus was measured with $H_z=350\mathrm{}\pm 10$ kOe and $H_x=700\mathrm{}\pm 10$ kOe. The ground-state Kramers doublet was uniquely determined from the value of both the magnetic hyperfine field and the quadrupole splitting, using a crystal-field-theory analysis and results of ab initio spin-polarized Hartree-Fock calculations for the $3d^{6}4s^1\left({}_{}{}^6{}_{}{}^{}D\right)$ and $3d^{6}4s^1\left({}_{}{}^4{}_{}{}^{}D\right)$ terms of monovalent iron. The agreement between theory and experiment was found to be excellent. A systematic study of the possible molecular compounds in the Fe-Xe (HI) mixtures was carried out. For high HI concentrations Fe${\mathrm{I}}_2$ and Fe${\mathrm{I}}_3$ were observed. For low iron concentrations and 1% HI in xenon only, the monovalent iron ion was observed after photodissociation of HI.