Formation of Fe i –B pairs in silicon at high temperatures

We report on the detection of Fe _i –B pairs in heavily B doped silicon using ⁵⁷Fe emission Mössbauer spectroscopy following implantation of radioactive ⁵⁷Mn⁺ parent ions (T _1/2?=?1.5 min) at elevated temperatures >?850 K. The Fe _i –B pairs are formed upon the dissociation of Fe _i –V pairs during the lifetime of the Mössbauer state (T _1/2?=?100 ns). The resulting free interstitial Fe_i diffuses over sufficiently large distances during the lifetime of the Mössbauer state to encounter a substitutional B impurity atom, forming Fe _i –B pairs, which are stable up to ～1,050 K on that time scale.     

Observation of Substitutional Fe in CEMS Measurements on Synthetic CVD Diamond

Hyperfine Interactions - Conversion electron Mössbauer spectroscopy measurements have been made on a diamond sample synthesized by chemical vapour deposition. The sample was implanted with 70...     

Whither HFI/NQI?

A brief review is given of the Hyperfine Interactions Conference series and, in particular, of the Joint meetings of the Hyperfine Interactions and Nuclear Quadrupole Interaction (HFI/NQI) Conferences, with respect to number of participants, contributed papers and participant countries. Trends are traced and recommendations are offered to attract a wider participation at future HFI/NQI conferences.     

Impadg-factor measurements in83Y

The IMPAD technique has been used to determine the Larmor precessions of the⁸³Y 595 keV 13/2⁺ and 145 keV 7/2⁺ states in iron. The net precessions found are ωτ(13/2⁺)=−9(2) mrad and ωτ(7/2⁺)=−92(5) mrad, leading to g-factors, g(13/2⁺)=+1.3(4) and g(7/2⁺)=+0.61(18). These results are discussed in terms of a partially decoupled [422]5/2⁺ Nilsson band.     

Residence sites for19F ions implanted into diamond

¹⁹F has been used to probe the structure of the diamond lattice. The measurements were performed via the time differential perturbed angular distribution (TDPAD) technique applied to the 197 keV state (τ=128 ns,Q=0.10 b) of¹⁹F. The nuclei were excited and recoil implanted into an oriented diamond using a (p,p′γ) reaction initiated by a pulsed 4 MeV proton beam. Model functions simulating a variety of residence sites for the probe ions in a single crystal were developed for the analysis of the data. The data implies the formation of two molecular types, or sites within the lattice, with possibly a third radiation damage component.     

Preface

Hyperfine Interactions -     

On the coexistence of oblate and prolate deformed bands in83Zr

Deformation parameters of the positive parity yrast band and negative parity bands in⁸³Zr are deduced from lifetimes andE2/M1 mixing ratios. Lifetimes of high spin states have been determined from recoil distance Doppler shift and Doppler shift attenuation measurements using the⁵⁴Fe(³²S,2pnγ) ⁸³Zr reaction. Ten lifetimes and five lifetimes limits were determined. The positive parity band, built on theg _9/2 K=5/2 orbital has an average deformation ¦β ₂¦=0.28(2), and shows a reduction ofE2 transition strengths in the observed backbend region at I^π≈21/2⁺. In contrast, theE2 strengths in the negative parity states show a steady increase up to I^π≈=15/2^?. These states are more strongly deformed than the positive parity states (¦β ₂¦=0.33(3)). TheE2/M1 mixing ratios show that the negative parity band hasK=3/2 and is prolate, and favour oblate deformation for the positive parity yrast band. In theK=1/2^? band theE2 strength of the 7/2^?→3/2^? transition yields a deformation ¦β ₂¦=0.26(5). The band structure is compared with calculations within the Hartree-Fock Bogoliubov cranking model.     

Emission Mössbauer spectroscopy study of fluence dependence of paramagnetic relaxation in Mn/Fe implanted ZnO

Emission Mössbauer Spectroscopy following the implantation of radioactive precursor isotope ⁵⁷Mn⁺ (T _1/2= 1.5 min) into ZnO single crystals at ISOLDE/CERN shows that a large fraction of ⁵⁷Fe atoms produced in the ⁵⁷Mn beta decay is created as paramagnetic Fe³⁺ with relatively long spin-lattice relaxation times. Here we report on ZnO pre-implanted with ⁵⁶Fe to fluences of 2×10¹³, 5×10 ¹³ and 8 × 10¹³ ions/cm² in order to investigate the dependence of the paramagnetic relaxation rate of Fe³⁺ on fluence. The spectra are dominated by magnetic features displaying paramagnetic relaxation effects. The extracted spin-lattice relaxation rates show a slight increase with increasing ion fluence at corresponding temperatures and the area fraction of Fe³⁺ at room temperature reaches a maximum contribution of 80(3)% in the studied fluence range.     

The lifetime of the 266 keV level in 206Tl

The lifetime of the ²⁰⁶Tl 2^? state at 266 keV has been measured by the delayed coincidence technique. The state was populated via the γ-decay of high-lying states excited in the ²⁰⁵Tl (d, p)²⁰⁶Tl reaction at E_d = 9.0 MeV. Delayed coincidences between a Si surface-barrier detector and a Ge(Li) detector resulted in a mean life for the 266 keV level of τ = 3.3(2) ns. The deduced B(E2) value of 171 (11) e² · fm⁴ indicates strong configuration mixing of two-hole states in this level.