Tellurium Isotopes Research Articles

Negative thermal ionization mass spectrometry of main group elements Part 2. 6th group: sulfur, selenium and tellurium

A systematic investigation of the formation of negative ions for the 6th main group elements using negative thermal ionization mass spectrometry (NTI-MS) is presented. A double-filament ion source with BaO on the ionization filament has been applied to reduce the work function of the rhenium filament material. S −, Se − and Te − were produced as most abundant ions. Low intensities of SeO −, SeO − 2, TeO − and TeO − 2 have also been detected. Although the electron affinity of SO 2 is low, high ion currents of SO − 2 have been observed from BaSo 4 samples. This may be due to an electron capture process of this molecule rather than to a thermal ionization process. A silica gel suspension mixed with the sample enhanced the Se − ion current by a factor of about 40 and the Te − intensity by a factor of about 10. However, the silica gel showed no enhancing effect on the S − ion current. An improvement in the precision of the selenium and tellurium isotope ratio measurements by a factor of up to 10 was obtained when using the silica gel technique as compared with previous NTI investigations. The data of the selenium isotope abundance measurements were accepted as “best measurements” by the IUPAC.

Neutron capture inTe122,123,124: Critical test forsprocess studies

The neutron capture cross sections of $^{122,123,124,125,126}\mathrm{Te}$ were measured in the energy range from 10 to 200 keV at the Karlsruhe Van de Graaff accelerator using gold as a standard. Neutrons were produced via the $^{7}\mathrm{Li}$(p,n${)}^{7}$Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4\ensuremath{\pi} barium fluoride detector. Several sets of measurements were performed under different experimental conditions to study the systematic uncertainties in detail. The cross section ratios \ensuremath{\sigma}(Te)/\ensuremath{\sigma}(Au) were determined with an overall uncertainty of \ensuremath{\sim}1%. This is an improvement by about a factor of 5 compared to existing data. Maxwellian-averaged neutron capture cross sections were calculated for thermal energies between kT=10 and 100 keV by normalizing the cross section shape up to 600 keV neutron energy reported in literature to the present data. These stellar cross sections were used in an s process analysis. With the classical approach the abundances of the three s only isotopes $^{122,123,124}\mathrm{Te}$ could be reproduced within the experimental uncertainties of \ensuremath{\sim}1%. The accuracy of the present data also allowed us to derive constraints for the existing stellar models with respect to the effective neutron density. Furthermore, the p process abundances for the tellurium isotopes are discussed.

The infrared spectrum of the TeD radical by laser magnetic resonance

Transitions in the fundamental and first two hot bands of the TeD radical have been detected by CO laser magnetic resonance. Resonances from the seven most abundant isotopes of tellurium, including the two with I = 1/2, have been identified and fitted to determine the parameters of a single effective Hamiltonian. The strongest signals were recorded as saturation (Lamb) dips.

Description of the ground-state pionic double charge exchange reaction on 128,130Te

The pionic double change exchange reactions 128,130Te( π +, π −) 128,130Xe are investigated within the proton-neutron random-phase approximation. The approach is fpund to give a satisfactory agreement of the calculated differential cross sections and angular distributions with recent data. A strong dependence of the calculated quantities on the strength g pp of the particle-particle force is observed. This behaviour is similar to that reported for the β + decay in neutron-dificient nuclei and the double beta decay. The role of the DCX for the interpretation of the ratio of the double beta decay half-lives of the tellurium isotopes is discussed.

Q ? -Measurements of indium, tin and antimony isotopes with massesA=128 and 130

β-decay energies of neutron rich tin, antimony and tellurium isotopes with mass numberA=128 and 130 were measured. The results obtained are discussed within the framework of earlier measurements. Additionally nuclear masses deduced from the experimentalQβ-values are compared with mass formulae predictions.

Tellurium Diffusion in the Mixed System CdxHg1−xTe

AbstractLattice dynamical calculations on the jump frequencies of different isotopes of tellurium in the mixed system CdxHg1−x Te are worked out following the general theory of diffusion for metals by Achar, assuming an active role for the vacancy. An isotope effect, which is a measure of the diffusion rate is also deduced. The lattice dynamics of this mixed system is worked out in the virtual crystal approximation using the rigid ion model of Plumelle and Vandevyver. The results indicate that diffusion is carried out prominently by the single vacancy mechanism.

Low-lying structures in the Gamow-Teller strength functions for the double-beta-decaying nuclei 76Ge, 82Se, 128Te, and 130Te.

Excitation-energy distributions of transition strength to ${1}^{+}$ states excited via the (p,n) reaction at 134.4 MeV on targets of $^{76}\mathrm{Ge}$, $^{82}\mathrm{Se}$, $^{128}\mathrm{Te}$, and $^{130}\mathrm{Te}$ were measured for excitation energies up to 25 MeV. Structures observed in the neutron spectra with forward-peaked (\ensuremath{\Delta}L=0) angular distributions were identified as ${1}^{+}$ states, except for the isobaric analog transitions. The total ${1}^{+}$ strength in these reactions was extracted by normalizing the intensity in the ${1}^{+}$ peaks to the Fermi transition strength observed in the isobaric analog state. The Gamow-Teller strength observed in ${1}^{+}$ peaks above a fitted polynomial background is typically 55% of the sum rule obtained by assuming that the strength of ${\ensuremath{\beta}}^{+}$ transitions is negligible. The portion of this strength found at excitation energies less than that of the Gamow-Teller giant resonance varied from 15% for $^{128}\mathrm{Te}$ to 38% for $^{76}\mathrm{Ge}$. Experimental results are compared with predictions of a shell model that includes a pairing force and a long-range Gamow-Teller force in both parent and daughter nuclei. A comparison of the strength functions of the tellurium isotopes is made; this comparison is relevant in determining whether double-beta decay without neutrino emission (0\ensuremath{\nu} decay) is observed in these isotopes.

The chemical states of tellurium produced by spontaneous fission of252Cf

The distribution of the chemical states of tellurium isotopes produced by252Cf spontaneous fission, collected separately in the matrixes of NaCl, Kl, NaF, CH3COONa·3H2O, Na2SO4 and NaNO3 crystals have been investigated. Two chemical states of tellurium isotopes maintained in these matrixes are Te(IV) and Te(VI). The relationships between the distribution of the chemical states of tellurium isotopes and the produced mode of tellurium, the chemical properties of collection matrixes, the time for collecting fission fragments are studied and the possible mechanism of the interactions of the fission products and the matrixes is discussed. The results show that the distribution of chemical states of tellurium isotopes depends on the chemical properties of the collection matrixes mainly.

E0 transitions in the light tellurium isotopes: evidence for intruder states

Conversion electron spectra have been measured for 118,120,122Te, following the beta decay of on-line mass-separated iodine isotopes. Several new Ipi =0+ states have been identified at low excitation energy. These, together with their E0 de-excitation strengths, provide evidence for the presence of intruder configurations, albeit mixed with the normal configurations. The experimental data are compared with IBM-2 mixing calculations.

An application of the dynamic deformation model to the tellurium isotopes

The recent developments of the dynamic deformation model (DDM) make it readily applicable to a wide range of nuclei. The authors report a study of the even-mass tellurium isotopes from N=68 to the closed neutron shell at N=82. Within this region there is experimental evidence for nuclei with the characteristics of vibrational, rotational or gamma -unstable level sequences. They show that the model is well able to account for these features as typified by level energies, electric quadrupole moments and gamma -ray transition probabilities across this region when the only parameter which changes is the neutron number. For comparison the experimental data were also fitted to IBM-2 and the results from these fits are in general in good agreement with those from the DDM.

Infrared Spectroscopy of TeF 6

Fourier transform and grating IR spectrometers and tunable diode lasers have been used to record the IR spectrum of TeF 6. The isotopic structure in the stretching fundamental ν 3is resolved, revealing a tellurium isotope shift of approximately 0.68 cm −1 amu −1. Some of the rotational structure in the P and R branches of ν 3 of 99.3% 130TeF 6 is also resolved and analyzed to yield a Coriolis constant ζ 3 = 0.225. Integrated absorptivities are reported for ν 3 and for the stronger combination bands. The isotope shifts and Coriolis constants are used to fix the general quadratic symmetry and valence force fields, and the force constants of the Group VI series SF 6, SeF 6, and TeF 6 are compared and discussed.

ESR identification of radiation-induced oxygen vacancy centers in paratellurite.

The ESR spectrum of paratellurite (\ensuremath{\alpha}-${\mathrm{TeO}}_{2}$) exposed to 1-MeV electron irradiation reveals a single spin-(1/2) defect in eight inequivalent sites with an anisotropic g value close to the free-electron value. Principal g values are 2.0105\ifmmode\pm\else\textpm\fi{}0.0005, 1.9705\ifmmode\pm\else\textpm\fi{}0.0005, and 1.9358\ifmmode\pm\else\textpm\fi{}0.0005. Resolved hyperfine structure is attributed to magnetic isotopes of tellurium in seven different sites neighboring each defect site. The g-value anisotropy together with the hyperfine structure suggest a positively charged, oxygen-vacancy model (${V}_{0}$(bu) with properties intermediate between those of the ${E}_{1}^{\mathcal{'}}$ center in ${\mathrm{SiO}}_{2}$ and the ${F}^{+}$ center in alkaline-earth oxides.

IBA-2 model calculation on even mass tellurium isotopes compared with results of recent nuclear orientation experiments

Calculations using the IBA-2 model code are presented for even-even tellurium isotopes118Te to124Te. Three parameter sets are used, two from previous work and a third chosen to give optimum fit to experimental positive parity energy levels and B(E2) ratios. With only two additional parameters, each with simple physical interpretation, the three parameter sets are shown to give excellent fits to the known collective negative parity states in these isotopes. Failure to fit the O 2 + ,O 3 + and 2 3 + levels suggests these may be 4p-2h intruder states, although their Behaviour with varying neutron number is not as clearly characteristic of such configurations as is found for the 2p-4h states in Cd isotopes.

R-process abundances near the mass 130 peak

view Abstract Citations (5) References (6) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS R-process abundances near the mass 130 peak de Laeter, J. R. ; Rosman, K. J. R. Abstract The Kaeppeler et al. (1982) reevaluation of r-process abundances in view of new neutron-capture cross section and elemental abundance data indicates that the height of the r-process peak near mass 130 is largely determined by the r-only process nuclides Te-128 and Te-130. It is presently noted that the work of Smith, De Laeter and Rosman (1977) has not been given due consideration in the assessment of the solar system's Te abundance. These data indicate a 25 percent reduction in the height of the mass 130 peak, in agreement with s-process systematics predictions. Publication: The Astrophysical Journal Pub Date: July 1983 DOI: 10.1086/161165 Bibcode: 1983ApJ...270..746D Keywords: Abundance; Nuclear Fusion; Solar System; Absorption Cross Sections; Tellurium Isotopes; Astrophysics full text sources ADS |

A new example of O(6) nuclear symmetry:52124Te72

The establishment of several excited 0+ states in 124Te provides a sensitive test which shows that the collective levels in this nucleus can be described by the O(6) limiting symmetry of the interacting boson model. Unlike other O(6) nuclei the spin-dependent L.L term in the Hamiltonian is negative and causes the highest spin levels in each multiplet to lie at lowest energy. It is suggested that the even tellurium isotopes may provide an opportunity to study the Su(5) to O(6) transition.

Relative Yields of Stable Tellurium Isotopes in Neutron-induced Fission

The relative isotopic abundances of four isotopes of tellurium (125, 126, 128 and 130) produced in the thermal neutron fission of 233U and 23SU have been measured for the first time by solid source mass spectrometry. Samples of 233U and 23SU were irradiated in a reactor and chemically separated by ion exchange techniques to permit nanogram-sized samples of fission product tellurium to be analysed mass spectrometrically. The results for 23SU are in good agreement with published radiometric values, whereas our results for 233U are the first experimental measurements in this mass range. The cumulative fission yields determined by mass spectrometry for ruthenium, palladium, cadmium, tin and tellurium show a smooth mass distribution in the symmetric region for both 233U and 235U, except for a significant depression in the yield curve in the range 111-14.

Changes in the structure of nuclei between the magic neutron numbers 50 and 82 as indicated by a rotating-cluster analysis of the energy values of the first 2 + excited states of isotopes of cadmium, tin, and tellurium

Values of R, the radius of rotation of the rotating cluster, are calculated from the observed values of the energy of the lowest 2(+) states of the even isotopes of (48)Cd, (50)Sn, and (52)Te with the assumption that the cluster is alpha, p(2), and alpha, respectively. R shows a maximum at approximately N = 58, a minimum at approximately N = 62, and a second maximum at approximately N = 70. The increase to the first maximum is interpreted as resulting from the overcrowding of spherons (alphas and tritons) in the mantle (outer layer) of the nuclei, causing the cluster to change from rotating in the mantle to skimming over its surface; the decrease to the minimum results from the addition of three dineutrons to the core, expanding the mantle and permitting the rotating cluster to begin to drop back into it; and the increase to the second maximum results from the overcrowding of the larger mantle surrounding the core containing the semi-magic number 14 of neutrons rather than the magic number 8 for N = 50. The decrease after the second maximum results from the further increase in the number of core neutrons to 20, corresponding to the magic number 82. Some additional evidence for the change to an intermediate structure between N = 50 and N = 82 is also discussed.

Alpha decay of neutron-deficient isotopes with 52 ≦ Z ≦ 55, including the new isotopes [formula omitted] and 110Xe

Using 58Ni( 58Ni,. xpγn) reactions and on-line mass separation, the α-decays of very neutron-deficient isotopes of tellurium, iodine, xenon and cesium were studied. The new isotopes 106 Te (T 1 2 = 60 − +μ s) and 110Xe were identified by their α-lines of 4160 ± 30 keV and 3737 ± 30 keV energy, respectively, with the genetic relationship between the two successive α-decays being verified experimentally, while for several other α-decaying isotopes more precise data were obtained. The observed α-decay properties are discussed within the systematics of energy and reduced width.

Mass analysis of milligram samples with the high current isotope separator MIERA

A facility has been developed whereby the high output electromagnetic isotope separator, MIERA, can be temporarily converted into a mass spectrometer. Milligram samples of highly enriched tellurium and cadmium isotopes have been analysed and the impurities have been determined to a precision of 0.02%. The necessary modifications are described. A measurement technique, which overcomes signal as well as background fluctuations, has been developed. The analysis of tellurium isotopes is given as an example to illustrate the mass spectrometer capability.

Indpeendent Yields of Iodine and Tellurium Isotopes in Fission of 232 Thorium with 30.5 MeV Alpha Particles

Iodine and tellurium isotopes produced in the fission of 232Th with 30.5 MeV alpha particles were separated using a method of sublimation in an air stream and the independent yields of 130I, 131I, 132m,gI, 133I 134I, 134m,gTe, 133mTe and 134Te (cumulative) were determined by means of high resolution Ge(Li) γ-ray spectrometry. A Gaussian fit to the experimental data was used to obtain the width parameter σz and the most probable charge Zp of the nuclear charge distribution in the isobaric chains 130 – 131. The most probable masses for fission fragments with Z = 52 and Z = 53 were also deduced from the measured fission yields.