Electric quadrupole interaction of 212Rn isomers in Bi

The electric quadrupole interaction of the ²¹² Rn 8⁺ and 6⁺ isomers in a Bi single crystal was measured. The experimental results together with a shell-model calculation of the quadrupole moments provide a calibration of the electric field gradient for Rn impurities in Bi, to be used in future quadrupole-moment measurements of Rn isomers. A two-level analysis procedure was employed for the combined data of the 8⁺ and 6⁺ isomers.     

Pressure dependence of the electric field gradient at Po impurities in Bi single crystal

The electric quadrupole coupling constants for²¹⁰Po(6⁺) isomers in a Bi single crystal host have been measured at ambient, 3 Kbar and 6 Kbar hydrostatic pressures. Assuming a linear pressure dependence of the EFG we find the logarithmic derivative dlnq/dP=–8(5)Mbar^–1. This result is analyzed in a quantitative way in a point charge model, considering the elastic and lattice constants of Bi, and in a qualitative way in the covalent bond picture.     

Electric quadrupole interaction in hafnium sulphates

A coincidence system is developed which gives a time resolution of =0,8 ns for the 133–482 keV -ray cascade of¹⁸¹Hf. It is applied to the study of EQI in hafnium sulphate salts. In the case of Hf(SO₄)₂ the interaction strength of _Q = 157.8 ± 0.5 MHz is obtained, together with the assymetry parameter =0.531±0.005 and the field distribution parameter =0.003±0.001. The data are compared with point-charge model calculations.A similar set of EQI data is also derived for another unstable and unidentified hafnium sulphate structure.     

Electric quadrupole interaction of recoil-implanted zinc in cadmium

The electric quadrupole interaction of the 605 keV 9/2⁺ state of ⁶⁷Zn in Cd metal was measured by the recoil implantation technique combined with the DPAD method (DIMPAD). The result, ν_Q = eQV_ZZ/h = 39.0(4) MHz (T = 373 K), is compared with the known quadrupole coupling constants in the Zn-Cd system.     

Electric quadrupole interaction of Ce isomers in tin

The quadrupole coupling constants for 10⁺ Ce isomers have been measured in a polycrystalline Sn host. The quadrupole moment ratios are Q[¹³⁸Ce(10⁺)]: Q[¹³⁶Ce(10⁺)]: Q[¹³⁴Ce(10⁺)]=11.45(14)1.71(16). The temperature dependence of the EFG was measured in the range 160–468 K.Incumbent of the Arye Dissentshik Career Development Chair.We thank Dr. A. Abbas for submitting to us the seniority scheme wave functions prior to publication.     

Electric quadrupole interaction of181Ta in Pd and Zn

A strong electric field gradient (EFG) has been observed at¹⁸¹ Ta in Pd and Zn metals using DPAC technique. The value of the EFG in Pd is found to be 12.5(8)×10¹⁷ V/cm² with an asymmetry parameter () of 0.33(2). The value of the EFG in Zn has the same value as in the Pd metal, but the asymmetry parameter has the value 0.36(3). The variation of EFG in Pd with temperature has shown a weak dependence. The results are interpreted in terms of oxygen trapping at Hf atoms during the sample preparation.     

Electric quadrupole interaction at181Ta in RNi5 compounds

The time differential perturbed angular correlation measurements in PrNi₅, NdNi₅, GdNi₅, DyNi₅ and ErNi₅ rare-earth intermetallics with¹⁸¹Ta as probe nuclei have revealed that these impurity nuclei experience a non-axial electric quadrupole interaction. In all the cases, except in GdNi₅, the interaction frequency has a single value in the range 15–20 MHz with asymmetry parameter 0.98. In GdNi₅, however, there are two interaction frequencies (13.61 MHz and 26.89 MHz), the former being the dominant one (90%) with 0.35 and the latter (10%) with 0.98. It is concluded that in all cases the probe nuclei experiencing the highly asymmetric electric field gradient (efg) occupy the unique Ni(3g) site. Annealing studies have shown that in the case of GdNi₅ the interaction gets highly damped, while there is negligible effect in the other cases. The temperature variation of the efg in all cases seems to follow the empiricalT ^3/2 relation.     

Exchange interaction and crystal field splitting of (La,Gd)B6 single crystals

The ESR on single crystals of (La, Gd)B₆ (c500 ppm) is reported. The splitting of Gd is determined as 50 mK. Theg-shift g=+0.018 and thermal broadeningb=9G/K show that in LaB₆ the conduction electrons are predominantly localized at the La site.     

Dissolved 210Po and 210Pb in Guarani aquifer groundwater,Brazil

The huge Guarani aquifer located in the South American continent is a very important resource for the region, and its drinking water quality has been investigated according to international standards, inclusive radiological parameters. This paper describes ²¹⁰Po and ²¹⁰Pb activity concentration data in groundwater samples collected at the Brazilian portion of Guarani aquifer, that is characterized by a great variability of temperature (18–70 °C), pH (4.0–9.9), sodium content (0.3–322 mg/l), bicarbonate content (0.1–318 mg/l), etc. Non-expensive alpha counting following some radiochemical steps for extracting and depositing dissolved ²¹⁰Po was used. The results of the measurements for samples collected in duplicate yielded a maximum ²¹⁰Po activity concentration of 3.7 mBq/L and a maximum ²¹⁰Pb activity concentration of 6.7 mBq/l, that are values greatly lower than the guidance level of 0.1 Bq/l established by the WHO for their presence in drinking water. The high sensitivity of the method allowed its applicability on the identification of complexes geochemical and hydrogeological processes occurring in Guarani aquifer as well on the evaluation of the drinking water quality in terms of dose calculations.     

Acousto-optic interaction in an InI single crystal

The acousto-optic figure of merit M ₂ of the InI single crystal has been measured using the Dixon method at a laser-radiation wavelength of 1.15 μm. The maximum measured value was M ₂ = 1100 × 10^–15 s³/kg. It is comparable with the figures of merit of the most efficient acousto-optic materials: TeO₂ and KRS-5. The velocities of longitudinal ultrasonic waves along the basic directions of the InI single crystal have also been measured.     

210Po in popular medicinal herbs from Poland

Herbs are an important part of traditional medicine in Poland. Therefore, the aim of this study was the determination of polonium ²¹⁰Po in 48 selected medicinal herb samples from the Polish market. The activity concentrations of ²¹⁰Po were measured using alpha spectrometry. The activity concentration of ²¹⁰Po was in the range from 0.3?±?0.1 to 28.2?±?0.4 Bq kg^–1. The obtained results were compared with corresponding studies conducted worldwide. A higher ²¹⁰Po activity concentration was observed in the above-ground part of plants. The obtained results show that the highest ²¹⁰Po activity concentration was observed in evergreen plants and winter-hardy plants. Yet even infusions with 2 g of the most contaminated herbs examined were considered to be radiologically safe.     

Electric quadrupole interaction of 100Rh in antimony, hafnium and rhenium

The effects of the Mg(II)/Fe(III) ratio on the structure and Fe microenvironments in MgFe LDH substances were investigated. The LDHs were prepared by the co-precipitation method with Mg(II)/Fe(III) ratios from 2:1 to 6:1. The materials were characterized by ⁵⁷Fe Mössbauer spectroscopy and powder X-ray diffractometry. The ⁵⁷Fe Mössbauer spectra exhibited asymmetric doublet corresponding to high-spin Fe(III) microenvironments in all LDH structure. It was found that the quadrupole splitting decreased with increasing Mg(II)/Fe(III)ratio reflecting change in the electric field gradient due to the incorporation of different amounts of iron into the Mg-containing layers.     

Raman scattering in the Bi2TeO5 single crystal

Polarized Raman spectra of the Bi₂TeO₅ single crystal have been investigated for the first time. The group-theoretic analysis of the first-order vibrational spectra is performed. The number of the experimentally observed bands is less than the predicted number of normal modes. The spectral ranges with similar bands are revealed. Some ranges in the spectra of Bi₂TeO₅ are identified from the spectral data for the materials containing bismuth-oxygen and tellurium-oxygen complexes.     

Zeeman nuclear quadrupole resonance study of a germanium tetrachloride single crystal

Zeeman studies of a single crystal of GeCl₄ have been carried out on a previously described pulsed FT NQR spectrometer. The technique for growing single crystals from liquid samples is described. The Zeeman-split spectrum for each of the resonances at μ₁ = 25.4493, μ₂ = 25.7133, μ₃ = 25.7354, and μ₄ = 25.7457 MHz reveals four quadruplets. The asymmetry parameters found lie in two groups of average values η = 0.035 and η = 0.078, much lower than the previously reported value of η = 0.35 obtained from a polycrystalline sample. The crystal of GeCl₄ is found to be orthorhombic with mmm or D_2h symmetry. From the directions of the field gradient axes the interbond angles have been calculated and show that the GeCl₄ molecule is a slightly distorted tetrahedron.     

Collinear acousto-optic interaction in a single tellurium crystal

The problem of designing acousto-optic imaging filters based on tellurium crystal is discussed. The measurement and calculation results of acousto-optic properties of tellurium are presented. The collinear acousto-optic interaction in tellurium crystal is experimentally implemented for the first time at the light wavelength of 10.6 μm.     

Electric quadrupole interaction at181Ta in tetragonal C16 intermetallic compounds

The TDPAC technique was employed for studies of the hyperfine interaction of¹⁸¹Ta in the Hf₂Ni and Zr₂Ni compounds with Al₂Cu-type structure. A linear temperature dependence of the quadrupole frequencies was measured in the temperature region 300–1100 K.