Nuclear Quadrupole Interaction at 187W(β-)187Re in Tungsten Compounds

1998 ◽  
Vol 53 (6-7) ◽  
pp. 323-339
Author(s):  
Pit Schmidt ◽  
Torsten Soldner ◽  
Wolfgang Tröger ◽  
Xinbo Ni ◽  
Tilman Butz ◽  
...  
Keyword(s):  
Experimental Data ◽  
Quadrupole Interaction ◽  
Asymmetry Parameter ◽  
Perturbed Angular Correlation ◽  
Nuclear Quadrupole Interaction ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Time Differential ◽  
Nuclear Quadrupole ◽  
Good Agreement

.6(The nuclear quadrupole interaction at 187W(β-)187 Re was determined by time differential perturbed angular correlation in WC, WS2, WSe2, WSi2, and CaWO4 to be (at 300 K): vQ = 335.9(2), 1094.9(1), 10311), 1131,5( 1), and 1085.9( 1) MHz, respectively. The asymmetry parameter ƞwas zero in all cases. For WSe2 and CaWO4 the temperature dependence of the nculear quadrupole interaction was determined between 300 K and about 900 K. Ab initio calculations of electric field gradients, using the WIEN95-code, were carried out for WC, WS2, WSe2, and WSi2 at W-sites and Re-impurities, and for CaWO4 at W-sites. Good agreement with experimental data was found.

A Comparative Time Differential Perturbed Angular Correlation Study of the Nuclear Quadrupole Interaction in HfF4·HF·2H2O Using 180mHf and 181Hf(β–)181Ta as Nuclear Probes: Is Ta an Innocent Spy?

2009 ◽  
Vol 64 (1-2) ◽  
pp. 103-111 ◽  
Author(s):  
Tilman Butz ◽  
Satyendra K. Das ◽  
Yurij Manzhur
Keyword(s):  
Electric Field ◽  
Frequency Distribution ◽  
Quadrupole Interaction ◽  
Nuclear Quadrupole Interaction ◽  
Electric Field Gradients ◽  
Rapid Loss ◽  
Field Gradients ◽  
Small Admixture ◽  
Time Differential ◽  
Nuclear Quadrupole

We report on a comparative study of the nuclear quadrupole interaction of the nuclear probes 180mHf and 181Hf(β −)181Ta in HfF4・HF・2H2O using time differential perturbed angular correlations (TDPAC) at 300 K. For the first probe, assuming a Lorentzian frequency distribution, we obtained ωQ= 103(4) Mrad/s, an asymmetry parameter η = 0.68(3), a linewidth δ = 7.3(3.9)%, and full anisotropy within experimental accuracy. For the second probe, assuming a Lorentzian frequency distribution, we obtained three fractions: (1) with 56.5(7)%, ωQ= 126.64(4) Mrad/s and η = 0.9241(4) with a rather small distribution δ = 0.40(8)% which is attributed to HfF4・HF・2H2O; (2) with 4.6(4)%, ωQ = 161.7(3) Mrad/s and η = 0.761(4) assuming no line broadening which is tentatively attributed to a small admixture of Hf2OF6・H2O; (3) the remainder of 39.0(7)% accounts for a rapid loss of anisotropy and is modelled by a perturbation function with a sharp frequency multiplied by an exponential factor exp(−λ t) with λ = 0.55(2) ns−1. Whereas the small admixture of Hf2OF6・H2O escapes detection by the 180mHf probe, there is no rapid loss of roughly half the anisotropy as is the case with 181Hf(β −)181Ta. This loss could in principle be due to fluctuating electric field gradients originating from movements of nearest neighbour HF adducts and/or H2O molecules after nuclear transmutation to the foreign atom Ta which are absent for the isomeric probe. Alternatively, paramagnetic Ta ions could lead to fluctuating magnetic dipole fields which, when combined with fluctuating electric field gradients, could also lead to a rapid loss of anisotropy. In any case, Ta is not an “innocent spy” in this compound. Although 180mHf is not a convenient probe for conventional spectrometers, the use of fast digitizers and software coincidences would allow to use all γ -quanta in the stretched cascade which would greatly improve the efficiency of the spectrometer. 180mHf could also serve as a Pu analogue in toxicity studies.

The 111mCd Nuclear Quadrupole Interaction in CdCl2 and its Monohydrate

1992 ◽  
Vol 47 (1-2) ◽  
pp. 89-95
Author(s):  
Th. Fraenzke ◽  
T. Butz ◽  
A. Lerf
Keyword(s):  
Angular Correlation ◽  
Quadrupole Interaction ◽  
Perturbed Angular Correlation ◽  
Nuclear Quadrupole Interaction ◽  
Temperature Range ◽  
Time Differential ◽  
Nuclear Quadrupole

AbstractThe 111mCd nuclear quadrupole interaction in CdCl2 and CdCl2 • H2O was determined in the temperature range from 77 K to 783 K and 363 K, respectively, by time differential perturbed angular correlation. In addition, both the crystallization of the monohydrate from solution and its dehydration were monitored in situ.

Motion of Cadmium Tracer Atoms in Al11R3 Phases (R=La,Ce,Pr)

2009 ◽  
Vol 289-292 ◽  
pp. 755-761 ◽  
Author(s):  
Stephanie Lage ◽  
Gary S. Collins
Keyword(s):  
Gamma Rays ◽  
Time Domain ◽  
Perturbed Angular Correlation ◽  
Nuclear Quadrupole Interaction ◽  
Electric Field Gradients ◽  
Jump Frequency ◽  
Field Gradients ◽  
The Mean ◽  
Nuclear Quadrupole ◽  
Jump Frequencies

Jump frequencies of Cd tracer atoms were measured in three phases having the orthorhombic Al11R3 structure, with R= La, Ce, or Pr. The structure has four inequivalent Al-sites and two inequivalent R-sites. 111In/Cd tracer atoms were observed to occupy several sites via the nuclear quadrupole interaction using perturbed angular correlation of gamma rays (PAC). Time-domain PAC spectra became damped as the temperature increased, which is attributed to nuclear relaxation caused by diffusional jumps of Cd tracer atoms leading to changes in orientations and/or magnitudes of electric field gradients (EFG’s). Maximum relaxations were observed near 770 K. A method is proposed for estimating the mean jump frequency at that temperature, giving a mean jump frequency w averaged over all sites of about 100 MHz. At still higher temperatures, damping decreased due to motional averaging, and the quadrupole perturbations evolved into unique signals having lower frequencies and corresponding in each phase to the averages of EFG tensors of all sites visited by the Cd tracer atoms. For Al11La3, the jump frequency at 1073 K was estimated to be 1.9 GHz. Such jump frequencies imply unusually high diffusivities in these phases.

Applications of Nuclear Quadrupole Interactions in Materials Research

1998 ◽  
Vol 53 (6-7) ◽  
pp. 340-348 ◽  
Author(s):  
Zhu Shengyun
Keyword(s):  
Angular Correlation ◽  
Quadrupole Interaction ◽  
Perturbed Angular Correlation ◽  
Nuclear Quadrupole Interaction ◽  
Quadrupole Interactions ◽  
Nuclear Quadrupole Interactions ◽  
Time Differential ◽  
Materials Research ◽  
Microscopic Studies ◽  
Nuclear Quadrupole

Abstract The principle of the time differential perturbed angular correlation and distribution technique which measures the nuclear quadrupole interaction is briefly described. Some examples are given to show the possibilities of this technique in microscopic studies of materials.

Electric Quadrupole Interaction at 181Ta in Isostructural Orthorhombic Cu8Hf3 and Cu8Zr3 Compounds

1998 ◽  
Vol 53 (6-7) ◽  
pp. 355-357
Author(s):  
P. Wodniecki ◽  
B. Wodniecka ◽  
A. Kulińska ◽  
A. Z. Hrynkiewicz
Keyword(s):  
Electric Field ◽  
Quadrupole Interaction ◽  
Perturbed Angular Correlation ◽  
Electric Quadrupole ◽  
Correlation Technique ◽  
Interaction Frequency ◽  
Electric Quadrupole Interaction ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Time Differential

Abstract The quadrupole interaction of 181Ta probes in isostructural Cu8Hf3 and Cu8Zr3 intermetallic compounds was studied in the temperature range 24 K -1100 K with the time-differential perturbed angular correlation technique. Two nonaxial electric field gradients corresponding to two nonequiv-alent hafnium or zirconium sites in the investigated structure were found. A linear decrease in the quadrupole interaction frequency with increase of temperature for the 8(d) sites was evidenced, while the vQ(T) dependence for the 4(c) sites is weaker and has a T3/2 character.

Impurity Quadrupole Interaction in Light Rare Earth Metals: 111Cd in La, Pr and Nd

1986 ◽  
Vol 41 (1-2) ◽  
pp. 99-103
Author(s):  
M. Forker ◽  
L. Freise ◽  
D. Simon
Keyword(s):  
Rare Earth ◽  
Quadrupole Interaction ◽  
Perturbed Angular Correlation ◽  
Rare Earth Metals ◽  
Nuclear Quadrupole Interaction ◽  
Light Rare Earth ◽  
Quadrupole Frequency ◽  
Time Differential ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole

The nuclear quadrupole interaction of dilutelight rare earth (RE) metals La, Pr and Nd by time differential perturbed angular correlationmeasurements. The quadrupole frequency νQ has been determined in Pr as a function oftemperature and pressure, in Nd as a function of temperature, and in La at 19 K. The pressuredependence of νQ of 111Cd in Pr ((d In νQ/d P)290 K = + 2.7 (2.3) · 10-3 Kbar-1) is a factor of3 - 4 weaker than in the heavy RE metals Gd to Er. At the same time the temperature dependenceof νQ in the light RE is up to a factor of 3 stronger than in the heavy RE. Between 300 K and900 K. the quadrupole frequency is a linear function of temperature with the same slope(d In νQ/dT)290 k = - 8.4(2) · 10-4 K-1 both in Pr and Nd. Between 25 K and 300 K the decrease is stronger than linear, and more pronounced in Pr than in Nd. The temperature coefficient(d In νQ/dT)290 k is found to decrease linearly with the RE atomic number across both the seriesof the fight and the heavy RE metals.

Oxygen Diffusion in YBa2Cu3O7–δ Studied via 133Ba(EC)133Cs Nuclear Quadrupole Interaction

1992 ◽  
Vol 47 (1-2) ◽  
pp. 12-20 ◽  
Author(s):  
W. Tröger ◽  
T. Butz
Keyword(s):  
Quadrupole Interaction ◽  
Oxygen Diffusion ◽  
Energy Barrier ◽  
Perturbed Angular Correlation ◽  
Nuclear Quadrupole Interaction ◽  
Nearest Neighbour ◽  
Time Differential ◽  
Nuclear Quadrupole ◽  
The Difference ◽  
Flowing Oxygen

AbstractThe oxygen diffusion in YBa2Cu3O7-δ was studied between 300 K and 1273 K in flowing oxygen by monitoring the 133Ba(EC)133 Cs nuclear quadrupole interaction by time differential perturbed angular correlation. The data are analyzed in a model of two different nearest neighbour oxygen configurations and yield hopping rates, the energy barrier and the difference in free enthalpy between both states. In addition, we studied the reduced system YBa2Cu3O6 +ε.

The 181Ta Nuclear Quadrupole Interaction in the Charge Density Wave Phases of 1T-TaS2

1990 ◽  
Vol 45 (3-4) ◽  
pp. 439-444 ◽  
Author(s):  
P. Ganal ◽  
T. Butz ◽  
A. Lerf ◽  
M. Naito ◽  
H. Nishihara
Keyword(s):  
Charge Density ◽  
Quadrupole Interaction ◽  
Charge Density Wave ◽  
Perturbed Angular Correlation ◽  
Density Wave ◽  
Nuclear Quadrupole Interaction ◽  
Time Differential ◽  
Charge Density Wave Phase ◽  
Correlation Spectrometer ◽  
Nuclear Quadrupole

Abstract With a high resolution time differential perturbed angular correlation spectrometer we investigated the nuclear quadrupole interaction of Ta in 1T-TaS2 . The results obtained for the commensurate charge density wave phase lead to a revised assignment of the previously observed 181Ta NQR resonances. Differences in the intracluster architecture of the 13-atom Star of David cluster between 1T-TaS2 and 1T-TaSe2 could be responsible for the metal to semiconductor transition which occurs in lT-TaS2 but not in lT-TaSe2 .

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