Mössbauer Experiments with Coulomb‐Excited ⁷³Ge after Coulomb Recoil Implantation

Abstract

The nuclear resonance absorption of the 67.03 keV de-excitation radiation of 73Ge*, Coulomb-excited by 20 to 30 MeV l80 ions, is studied. The recoiling 73Ge* nuclei are implanted into a chromium substrate. The electronic configurations Ge (4s' ps) in Ge (cryst.), Ge (15% (4s2 PO), 85% (4sa p2)) in Ge (II)Se, Ge (62% (4s0 PO). 38% (4s' p3)) in GeO, (hex.) and GeO, (tetr.), andthe ratio SR/R=1.12 x lO-sof the nuclear charge radius are compatible with the measured isomeric shifts. Line broadening6 and recoil-free fractions f of the implantation target and the absorbers are determined. A t 78 OK fGeO,(tetr.) is greater than fGeO,(hex.) by a factor of six.Die Kernresonanzabsorption der 67.03 keV y-Strahlung von 73Ge*, Coulomb-angeregt durch 180-Ionen von 20 bis 30 MeV, wurde untersucht. Die riickgestoBenen 73Ge*-Kerne wurden in eine Chromunterlage implantiert. Die Elektronenkonfigurationen Ge (4s1p3) in Ge (krist.), Ge (15% (48, PO), 86% (48, p2)) in Ge(II)Se, Ge (62% (4s0 PO), 38% (4s' p3)) in GeO, (hex.) und GeO, (tetr.) und 6R/R = 1,12 x 10-3 des Kernladungsradius sind mit den gemessenen Isomerieverschiebungen vertriiglich. Linienbreiten und Debye-Waller-Faktoren f des Implantationstargets und der Absorber wurden bestimmt. Bei 78" K ist faeO,(tetr.) urn den Faktor6 groBer als fGeo,(hex.).

Nuclear forward scattering by the 68.7 keV state of 73 Ge in CaGeO 3 and GeO 2

“…73 Ge solid-state NMR revealed a quadrupolar coupling constant C Q = 19.3(5) MHz [15]. MS, however, revealed no observable hyperfine interactions and single-line spectra [3,4] for both GeO 2 phases. We thus expect the NFS spectra of both phases to obey eq.…”

“…The lines are the fits according to the Debye approximation [17]. Open symbols correspond to MS results [3,4] and XRD results [18][19][20][21][22].…”

“…The lattice dynamics were studied by the determination of the Lamb-Mössbauer factor and the Debye temperature. The GeO 2 measurements allowed us to validate the results obtained by MS [3,4]. We performed measurements with an applied magnetic field in order to determine the so far unknown nuclear magnetic moment μ e of the 73 Ge excited state.…”

MÖSSBAUER EXPERIMENTS WITH COULOMB-EXCITED57Fe AFTER RECOIL IMPLANTATION INTO fcc-LATTICES

“…A large fraction of the excited Mossbauer atoms can be implanted into a host lattice, where they de-excite emitting a gamma ray. The slowing down mechanism of the implanted atoms can be devided into two characteristic stages [3] : Above a few ten keV the kinetic energy loss is mainly due to electronic excitation and ionisation of the lattice atoms. Below ten keV the excitation of lattice vibrations and the displacement of lattice atoms dominate in the stopping process.…”

“…A direct implantation, as used earlier with 61Ni [4] and 73Ge [3] [5], is not appropriate in our case for the following reasons :…”