Nuclear forward scattering by the 68.7 keV state of ⁷³Ge in CaGeO₃ and GeO₂

¹ Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH - D-52425 Jülich, Germany, EU
² Faculté des Sciences, Université de Liège - B-4000 Liège, Belgium, EU
³ Deutsches Elektronen-Synchrotron - D-22607 Hamburg, Germany, EU
⁴ Bayerisches Geoinstitut, Universität Bayreuth - D-95440 Bayreuth, Germany, EU
⁵ Laboratoire de Minéralogie, Université de Liège - B-4000 Liège, Belgium, EU

Received: 2 August 2013
Accepted: 23 September 2013

Abstract

We measured nuclear forward scattering of synchrotron radiation by the 68.7 keV nuclear resonance of ⁷³Ge with a half-life . The Debye temperatures of CaGeO₃ in the wollastonite, garnet and perovskite phases were determined to be 386(20) K, 437(20) K and 507(20) K, respectively, and 309(20) K and 459(11) K for GeO₂ in the quartz and rutile phases, respectively. The isomer shift is clearly dependent on the Ge valence but not directly on the coordination geometry. The so far unknown magnetic moment μ_e of the 68.7 keV excited state of ⁷³Ge is determined to be . Time domain ⁷³Ge Mössbauer spectroscopy with the 68.7 keV resonance is feasible for isomer shift and Debye temperature measurements but so far neither electric quadrupole nor magnetic hyperfine interactions could be observed.