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1.
The magnetic hyperfine field of Se in nickel was measured by means of the time-differential perturbed angular correlation
(DPAC) technique, using the 755–250 keV γ-ray cascade fed in the decay of77Br. A value ofB
hf(NiSe)=+15.11(35) T was obtained at room temperature. The half-life of the 250 keV state and the anisotropy of the 755–250 keV
cascade were found to beT
1/2=9.68(6) ns andA
22=−0.454(9), respectively. 相似文献
2.
Correia J. G. Haas H. Araujo J. P. Marques J. G. Soares J. C. Melo A. A. 《Hyperfine Interactions》2001,136(3-8):155-159
Conversion electron-gamma PAC measurements of the 49–37 keV cascade in 80Br through the intermediate 2− state with T
1/2=7.4 ns were performed with a system of two magnetic lens spectrometers and two BaF2 scintillation detectors. The parent 80mBr activity with a halflife of 4.4 hrs was implanted into Ni, Zn and graphite at the ISOLDE separator at CERN. The observed
interaction frequency in the nickel matrix is in good agreement with the known value of the hyperfine field for Br in Ni and
the magnetic moment of the 2− state. From the measured quadrupole interaction in Zn and graphite the electric field gradients at Br were obtained.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
3.
C. Hohenemser A. R. Arends H. de Waard H. G. Devare F. Pleiter S. A. Drentje 《Hyperfine Interactions》1977,3(1):297-314
Lattice damage after implantation of111In in Ni has been studied applying the DPAC technique to the 171–245 keV -ray cascade in the daughter nucleus111Cd. Implantations were carried out at 10 K and at 300 K. The low temperature implantation yields a higher regular substitutional fraction (80%) than the room temperature implantation (40%). The annealing behaviour of both implants above RT is the same. In addition, two distinct defect-associated sites were observed in isochronal annealing sequences. A microscopic model for these defects is presented, which takes into account magnetic and electric hyperfine interaction strengths, binding energies and site populations as a functions of temperature. 相似文献
4.
Nuclear orientation measurements are used to determine the hyperfine hamiltonian for82Br implanted into Fe single crystals (dose 5×1014/cm–2 implant energy 80 keV). Using a model based upon channeling measurements a good fit to the temperature-dependent gamma anisotropy is obtained for a pure magnetic interaction experienced by the 36±5% of Br which implants substitutionally of magnitudeB
hf (substitutional)=840±120 kG, withB
hf (non-substitutional)<150 kG. This hamiltonian is used to deduce unknown multipole mixing ratios in the daughter82Kr decay. Hyperfine field systematics are shown to indicate a substitutionalFeBr field of 1000 kG, and the origins of this field and the smaller interstitial interaction are discussed. 相似文献
5.
Goto J. Ohya S. Ohtsubo T. Kawamura Y. Muto S. Nishimura K. Tanigaki M. Taniguchi A. Ohkubo Y. Kawase Y. 《Hyperfine Interactions》2001,136(3-8):561-566
Low-temperature nuclear orientation (LTNO) experiments were performed on 151Pm implanted into iron and 147Nd implanted into nickel. The γ-ray anisotropy measurements yielded values of the magnetic hyperfine field and the substitutional
fractions of these ions in the host metals. An observed discrepancy between the substitutional fractions obtained from the
91 keV and 531 keV data on 147NdNi is briefly discussed.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
6.
Radioactive151Dy ions were implanted at room temperature into a polycrystalline nickel foil to a total dose of 2.1014 at/cm2. Mössbauer spectroscopy was performed on the 21.54 keV transition of151Eu occuring in the decay of151Gd. The results show that Eu is trivalent in this host and that the large majority of the Eu atoms is located on substitutional lattice sites. The low-temperature magnetic hyperfine field was determined as Bhf=75.1(7) T. From this value the magnitude of the exchange field acting on the Eu3+ spin could be derived: Bex=?49(7) T. The temperature dependence of the hyperfine field suggests that the spinorbit coupling acting in the Eu3+ core is about 15% lower than in insulating compounds. 相似文献
7.
We obtained57Fe hyperfine field parameters from Fe1−x-Co
x
alloys (0≤x≤0.6) from 77 K to 900 K. We first discuss the origin of the low temperature hyperfine fields in terms of the 3d and 4s electrons
at57Fe atoms. The57Fe hyperfine magnetic field (hmf) of Fe-Co alloys depends more weakly on temperature than the hmf of pure Fe. This temperature
dependence occurs because the alignment of the magnetic moments at both the Fe atoms and at the Co atoms depend on temperature
in the same way as the bulk magnetization of Fe-Co alloys. 相似文献
8.
Mihara M. Hashimoto K. Arimura K. Kudo S. Akutsu K. Minamisono K. Miyake T. Fukuda M. Matsuta K. Minamisono T. 《Hyperfine Interactions》2001,136(3-8):339-343
The hyperfine interactions of short-lived β-emitter 12B implanted into a CaB6 crystal have been studied by means of the β-NMR technique. An electric quadrupole splitting has been observed at room temperature
from which an electric field gradient of q=−(1.34±0.05)×1021 V/m2 was determined. From the present result, it was found that the 12B nuclei are mainly implanted in the substitutional boron site.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
9.
400 keV111In+ ions were implanted into CuO powder. After annealing at 570 K, more than 50% of the implants were found on substitutional
sites in the monoclinic CuO lattice. PAC-spectra taken below the Néel temperatureT
N≈230 K revealed a broadening of the quadrupole spectrum and additional satellite frequencies caused by combined electric and
magnetic hyperfine interaction. Assuming that the orientation of the electric field gradient is given by the point charge
model and taking the 〈010〉 direction of the supertransferred fieldB
tr in CuO from neutron diffraction, we find a Larmor frequency of ωL≈40 MHz corresponding toB
tr≈2.7 T at 60 K.
Supported in part by BMFT under contract FK213N54930. 相似文献
10.
Silicon samples have been boron implanted at 150 keV at liquid nitrogen temperature to a dose of 3.6 × 1015/cm2. This dose rendered the implanted layer amorphous as viewed by helium ion backscattering. Four kinds of room temperature measurements were made on the same set of samples as a function of the isochronal annealing temperature. The measurements made were the determination of the substitutional boron content by the channeling technique using the B11(p, α) nuclear reaction, observation of the disorder by helium ion backscattering, determination of the carrier concentration by van der Pauw Hall measurements, and the sheet resistivity by four point probe measurements. These measurements are compared with results from samples implanted at room temperature. The carrier concentration correlates well with the substitutional boron content for both room temperature and liquid nitrogen temperature implantations. Following annealing temperatures in the 600 to 800°C range, a much larger percentage of the boron lies on substitutional lattice sites, and therefore the carrier concentration is larger, if the implantation is done at liquid nitrogen temperature rather than at room temperature. Following liquid nitrogen temperature implantation, reverse annealing is observed from 600 to 800°C in the substitutional boron content, carrier concentration and sheet resistivity. The boron is more than 90 per cent substitutional after annealing to 1100°C for both the room temperature and liquid nitrogen temperature implantations. The low temperature implantation produced a buried amorphous layer, and this layer was observed to regrow from both the surface and substrate sides at approximately equal rates. 相似文献
11.
A. G. Bibiloni M. C. Caracoche A. R. Lopez García J. A. Martinez L. A. Mendoza Zelis R. C. Mercader A. F. Pasquevich 《Hyperfine Interactions》1977,5(1):381-389
The hyperfine interaction of140Ce in nickel has been investigated by the time-differential perturbed-angular-correlation technique (TDPAC). The probe was produced by isotope separator implantation of the fission product140Xe, the - decay chain of which finally populates excited states of140Ce.Different spin rotation spectra were observed before and after an 8 h annealing at 415°C. The analysis of the spectra led to the conclusion that the Ce ions were in the diamagnetic 4+ state. The dominant contributions to the hyperfine interaction are two different magnetic hyperfine fields: |H
hf
1|=385±7 kOe and |H
hf
2|=276±12 kOe.H
hf
1 disappears after annealing. The fraction of nuclei which observeH
hf
2 is increased by the annealing procedure from 16% to 75%. It is assumed thatH
hf
1 is the hyperfine field of CeNi in an unperturbed substitutional site andH
hf
2 is attributed to Ce ions which have trapped a single vacancy. 相似文献
12.
T. Zemčík 《Hyperfine Interactions》1990,55(1-4):1099-1102
A systematic increase of the average hyperfine magnetic induction at57Fe measured at room temperature during interrupted isothermal annealing was found to be inherent to the irreversible relaxation
processes in the Fe−B based soft magnetic alloys at moderately elevated temperatures. Assuming superimposed asymptotic exponential
field vs. time dependences. several processes can be distinguished, their relaxation times determined and from the Arrhenius-like
log τ vs. 1/T plots average activation enthalpies estimated. Results on the Fe70Co10B20 and Fe85−x
Co
x
B15 (x=17, 19 and 21 at. % Co) amorphous ribbons between 100 and 200°C are compared and discussed in terms of possible stress relief,
free volume annihilation and short range ordering mechanisms. 相似文献
13.
A. G. Griffiths C. J. Ashworth I. S. Grant J. Rikovska N. J. Stone P. M. Walker W. B. Walters J. P. White 《Hyperfine Interactions》1988,43(1-4):481-488
The nuclear ground state spins of the odd-A Br nuclides75, 77, 79Br with Z=35 are all 3/2−. Nilsson orbital calculations show that the 35th proton occupies the f5/2 [301]3/2− orbital for ε<0.20 and the p3/2 [312]3/2− orbital at larger deformations. The magnetic moments of these two states differ by a factor of two, giving clear evidence
for the magnitude of the ground state deformation. Low Temperature Nuclear Orientation measurements made in Oxford and Bonn
on76, 77gBrFe prepared at ISOLDE, and on line at the SERC Daresbury Laboratory on72, 74m, 75BrFe, have yielded the magnetic moments of these isotopes, using a two non-zero field model with magnetic hyperfine fields of
+81.38(6) T and 26(2) T. The spin of the73Br ground state is also deduced. An interpretation of the ground state configurations of these isotopes is given. 相似文献
14.
The magnetic hyperfine field of Ta in iron was measured by means of DPAC using the 5/2+ state in181Ta. At room temperature, this field was found to be |H
hf(RT)|=6.08(7) T, which confirms the result of an earlier DPAC experiment. A hyperfine anomaly5/2Δ7/2=−4.6(23)% between the above state and the 7/2+ ground state of181Ta is deduced. 相似文献
15.
H. C. Jain 《Hyperfine Interactions》1985,26(1-4):941-962
The decoupling experiments involving the time-differential perturbed angular correlation (TDPAC) of the 133–482 keV γ-γ cascade
in the presence of an external magnetic field applied along the quantization axis have been performed to measure the electric
quadrupole and the magnetic hyperfine interactions experienced by the181Ta nuclei at Hf sites in the pseudobinary compounds HfFe2-xSix, withx=0.1 andx=0.3. The hyperfine magnetic fields measured at 298 K areH
hf=133.1±12.0 kG in the cubic (C15) Laves phase compound HfFe1.9Si0.1 andH
hf=76.8±7.0 kG in the hexagonal (C14) Laves phase compound HfFe1.7Si0.3. The decoupling technique has also been used to obtain a —ve sign for the hyperfine field experienced by181Ta nuclei at the Ti or Hf sites in the Heusler compound Co2Ti0.8Hf0.2Sn and a+ve sign for the hyperfine field at Zr sites in the cubic (C15) Laves phase compound ZrFe2. 相似文献
16.
A.N. Andreyev K. Van de Vel A. Barzakh A. De Smet H. De Witte D.V. Fedorov V.N. Fedoseyev S. Franchoo M. Górska M. Huyse Z. Janas U. Köster W. Kurcewicz J. Kurpeta V.I. Mishin K. Partes A. Plochocki P. Van Duppen L. Weissman 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):63-75
Alpha-decay properties of the neutron-deficient isotope 185Pb were studied at the PSB-ISOLDE (CERN) on-line mass separator using the resonance ionisation laser ion source (RILIS). The
nuclei of interest were produced in a 1.4 GeV proton-induced spallation reaction of a uranium graphite target. In contrast
to previous studies, two α-decaying isomeric states were identified in 185Pb. The relative production of the isomers, monitored by their α-counting rates, could be significantly changed when a narrow-bandwidth
laser at the RILIS setup was used to scan through the atomic hyperfine structure. Based on the atomic hyperfine structure
measurements, along with the systematics for heavier odd-mass lead isotopes, the spin and the parity of these states were
interpreted as 3/2- and 13/2+ and their nuclear magnetic moments were deduced. The α-decay energy and half-life value for the I
π = 13/2+ isomer are E
α = 6408(5) keV, T
1/2 = 4.3(2) s, respectively; while for the I
π = 3/2- isomer ( T
1/2 = 6.3(4) s) two α-decays with E
α1 = 6288(5) keV, I
α1 = 56(2)% and E
α2 = 6486(5) keV, I
α2 = 44(2)% were observed. By observing prompt α-γ coincidences new information on the low-lying states in the daughter isotope
181Hg was obtained.
Received: 7 February 2002 / Accepted: 19 February 2002 相似文献
17.
P. Herzog U. Dämmrich K. Freitag C. -D. Herrmann K. Schlösser 《Zeitschrift für Physik B Condensed Matter》1986,64(3):353-356
Nuclear magnetic resonance of82Br oriented at low temperature in iron has been observed with a sample prepared by ion implantation atT<0.2 K. The asymmetric resonance signal can be decomposed in a broad background signal and a narrow line of FWHM=1.8 (4) MHz which can be attributed to82Br in undisturbed substitutional sites of Fe. From the center frequency of this narrow line (B
ext=0)=201.86(13) MHz we derive the magnetic hyperfine field asB
hf(BrFe)=81.38(6) T. This value is considerably larger than the result of theoretical calculations. 相似文献
18.
J. Prinz I. Berkes P. Herzog B. Hlimi M. De Jesus M. Massaq I. Romanski 《Hyperfine Interactions》1992,75(1-4):275-282
First experiments in the systematic study of the structure of ground states and isomeric states of Br isotopes as function
of neutron number at ISOLDE, CERN are reported. The isotopes74g.74m,77,78,84g,84mBr have been implanted into iron and studied with the techniques of low temperature nuclear orientation and nuclear magnetic
resonance of oriented nuclei (NMR/ON). The experiments were performed with the NICOLE on-line nuclear orientation set-up using
the isotope separator ISOLDE-3. NMR/ON experiments were successful for74mBr with continuous on-line implantation and for77Br. Using as value of the hyperfine field Bhf(BrFe)=+81.3S (3) T we obtain |g (74mBr)|=0.455 (3) and |g (77Br)|=0.6492 (3). Static nuclear orientation data have been measured for all above mentioned isotopes. From these data we derive
|μ(78Br, I=1)|=0.13 (3) and |μ(84gBr, I=2)|=1.9 (7). The results are discussed within the systematics of the bromine isotopes. 相似文献
19.
The magnetic hyperfine interaction of Cu in Fe, Co and Ni was studied by means of the γ-γ perturbed angular correlation method
using62Zn(62Cu) as a probe. With the publishedg-factor (g=+0.661(12)) of the 41 keV, 2+ state hyperfine fields ofB
HF=16.95(51) T,B
HF=13.15(41) T andB
HF=4.05(30) T atT=0 K for Cu in Fe, Co and Ni are derived, respectively. The systematic discrepancy of these values with several independent
measurements of these hyperfine fields is removed by deriving a new value ofg=0.55(5) for the 41 keV, 2+ state of62Cu. 相似文献
20.
F. Raether D. Wiarda K. P. Lieb J. Chevallier G. Weyer 《Zeitschrift für Physik B Condensed Matter》1989,73(4):467-478
The magnetic-dipole and electric-quadrupole hyperfine interactions of111Cd probes in fcc cobalt after implantation of radioactive111In+ ions have been investigated by PAC measurements with fast BaF2 detectors. Six different sites of the probe atoms could be distinguished and characterized by their hyperfine parameters and annealing behaviour. Besides the substitutional site, three sites are assigned to In-vacancy complexes which are formed athermally in the implantation process or by thermally-activated trapping of lattice defects in annealing stage III. The remaining two sites are attributed to In located in stacking faults or hcp regions of the host. Systematic trends of impurity hyperfine fields in defect sites become evident from a comparison with other impurity-host combinations. The temperature dependence of the magnetic hyperfine fields has been measured between 20 K and 390 K. Large differences found for the various sites are discussed. 相似文献