Nuclear orientation of125I in n-Si and p-Si using defect induced electric field gradients

Defect induced electric field gradients were generated by ion implantation of¹²⁵I in highly B-doped p-Si and P-doped n-Si. The resulting low temperature nuclear orientation at the parent¹²⁵I state was detected by¹²⁵Te Mössbauer spectroscopy. From the asymmetry of the Mössbauer spectrum, the sign of the quadrupole interaction can be derived. This sign is found to be the same for n-Si as for p-Si.     

Stability of the Fe3 + state in ZnO

We review the state-of-the-art status of the research on the phase diagram of QCD matter out of quarks and gluons. Our discussions particularly include the extreme environments such as the high temperature, the high baryon density, and the strong magnetic field.     

Mössbauer study of the microscopic surrounding of co atoms implanted in si and ge below the full amorphization limit

Mössbauer spectroscopy on ⁵⁷Co implanted into Si and Ge at doses between 10¹¹ and 10¹⁵ atoms/cm² supports the single track amorphization model. Calculations based on linear cascade theory do not give quantitative agreement with the experiment.     

The lattice location of133Xe implanted in pyrolitic graphite studied by Mössbauer effect

Pyrolytic graphite was implanted with¹³³Xe at a dose of 5·10¹⁷ atoms/m². The large anisotropy of the recoilless fraction of the¹³³Cs daughter isotope suggested that the Xe is situated in between the carbon layers in the lattice. The cesium was found in the Cs⁺ ionization state.Research Associate, NFWO.     

Mössbauer spectroscopy study of iodine and tellurium atoms in solid argon

Mössbauer effect studies were performed on the nucleogenic ¹²⁵Te and ¹²⁹I monomers formed by the decay of their respective parents ^125mTe and ^129mTe embedded in solid argon at 4.2 K. Rare-gasmatrix-isolation (RGMI) and ion implantation techniques were combined to produce those extremely diluted Mössbauer emitters. The ¹²⁵Te spectrum is composed of a quadrupole split component with splitting $\text{e}{}^2\text{qQ}\text{2}\text{= 9.2(4)}\text{mm}\text{s}$ and isomer shift $\text{IS = + 0.35(5)}\text{mm}\text{s}$, and a single line component with $\text{IS = +0.15(5)}\text{mm}\text{s}$ with respect to a ZnTe absorber. They are attributed to Te⁰ and Te^?1 species, respectively. The ¹²⁹I spectrum is composed of a single quadrupole split component with $\text{e}{}^2\text{qQ = ?685(20) MHz and IS = +0.75(4)}\text{mm}\text{s}$ with respect to a ZnTe source. This species is attributed to I⁰. Two novel single-line absorbers with high f values at RT were developed for the Te and I experiments, e.g. Mg₃TeO₆ and Na₅IO₆. Based on our results for Te⁰ and Te^?1 and on relativistic Dirac-Slater atomic calculations, a new IS calibration curve under the form of a nonlinear relationship of IS versus the number of p holes (h_p) in the closed shell configuration of 5s²5p⁶ is established for ¹²⁵Te. The IS data of the I⁰ monomer are used to refine the IS(h_p) relationship for ¹²⁹I. From these new calibration curves values are deduced for the change in mean-squared charge radius Δ〈r²〉 = 3.4(3) 10^?3fm² for ${}^{125}\text{Te and Δ〈r}{}^2\text{〉 = 19.9(7) 10}{}^{\mathrm{?3}}\text{fm}{}^2$ for ¹²⁹I, respectively. The origin of the quadrupole interaction and the experimental features of this RGMI-implantation-Mössbauer emission spectroscopy are fully discussed.     

The influence of oxygen on the lattice sites of rare earths in silicon

We have used conversion electron emission channeling to investigate the lattice sites of ^167mEr following implantation of the radioactive isotope ¹⁶⁷Tm into CZ Si and FZ Si at varying doses (6×10¹² – 5×10¹³ cm⁻²). In all cases isothermal annealing at 900°C caused Er to leave its preferred near-tetrahedral sites in favour of random lattice sites, but this process occurred by orders of magnitude faster in CZ Si. Furthermore, in CZ Si the incorporation of Er on random lattice sites was fastest in samples implanted with low doses of Tm+Er. We compare our experimental results to a simple numerical model which accounts for the diffusion of Er and O and the formation of Er_nO_m complexes. On the basis of this model, our experimental data indicate that only a few (probably between 1 and 2) O atoms are required in order to remove an Er atom from its tetrahedral site.     

Supersymmetry and Kac-Moody algebras

The invariance algebra of the Majorana action contains a Kac-Moody algebra which, on shell, reduces to an Abelian algebra. In the absence of auxiliary fields in the Wess-Zumino model, supersymmetry transformations generate an infinite-dimensional Lie algebra, which is shown to be a Grassmannian extension of this Kac-Moody algebra. The corresponding Noether charges are discussed.     

Observation of a small quadrupole interaction in 129IFe Mössbauer spectra

From an asymmetry in the line intensities in ${}^{129}\text{I}\text{Fe}$ Mössbauer spectra, a small quadrupole interaction is inferred.