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1.
A. Damarupurshad R. J. Hart J. P. F. Sellschop H. O. Meyer 《Journal of Radioanalytical and Nuclear Chemistry》1997,219(1):33-39
Instrumental neutron activation analysis (INAA) has been applied to the analysis of 62 small (0.01–0.5 carat), single, inclusion-bearing and inclusion-free diamonds from South Africa, Brazil and Colorado. Up to 40 elements were detected at the ppb and ppt levels in individual diamonds of the eclogitic (basaltic affinity) and the peridotitic (ultramafic) paragenesis. The data obtained in this study can be used to distinguish between diamonds from the eclogitic and peridotitic parageneses and provides geochemical information on the environment in which diamonds crystallize. Further, the technique may prove to be useful in fingerprinting diamonds of different provenance areas. 相似文献
2.
Sources of error in the fast neutron activation analysis determination of oxygen have been investigated and minimised. The oxygen contents of eighteen international rock standards and a sulphide ore standard have been determined, and compared with the values calculated by difference using the reported full analyses. Accuracies of 0.3% average deviation and reproducibilities of ±0.2% standard deviation have been obtained, where oxygen contents exceeded 1.0 g. 相似文献
3.
J. H. Raudies H. Appel G. M. Then W. -G. Thies K. Freitag J. P. F. Sellschop M. E. Stemmet 《Hyperfine Interactions》1983,15(1-4):487-490
181Hf ions were implanted at (900±10)K into (100) cleaved single crystal diamonds. After subsequent annealing residence site parameters were determined for the implanted ions employing the (133 keV)–(482 keV) cascade in181Ta in TDPAC technique. Fractions of 5% each were determined that experience axially symmetric electric field gradients (EFG) Vzz(1)=5.5×1017 V cm–2 and Vzz(2)=9.6×1017 V cm–2, respectively. The bulk of the ions are strongly disturbed by still higher electric field gradients. 相似文献
4.
S. Connell K. Bharuth-Ram H. Appel J. P. F. Sellschop M. Stemmet 《Hyperfine Interactions》1987,36(3-4):185-200
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. 相似文献
5.
K. W. Allen R. J. Keddy J. P. F. Sellschop B. Whittle 《Zeitschrift für Physik A Hadrons and Nuclei》1988,330(1):117-118
The M1 gamma decay strengths of the ground state transitions of the 1+,T=1 states of40Ca at 9.86 MeV and 10.32 MeV have been measured using the reaction39K(p,γ)40Ca. The measured ground state gamma decay widths of these levels are 1.06±0.15 eV and 5.8±0.8 eV respectively. These relatively large M1 strengths can be explained by a shell model calculation incorporating excited core configurations. 相似文献
6.
J. Carter R.G. Clarkson V. Hnizdo R.J. Keddy D.W. Mingay F. Osterfeld J.P.F. Sellschop 《Nuclear Physics A》1976,273(2):523-532
Angular distributions for 16O + 24Mg and 12C + 24Mg elastic and inelastic (2+, 1.37 MeV state in 24Mg) scattering have been measured at energies spanning the Coulomb barrier. Apart from the structure typical of strong destructive Coulomb-nuclear interference, the data exhibit some additional specific features. Coupled channel calculations were performed, along with DWBA calculations to analyse the data using fixed coupling strengths deduced from the results of Coulomb excitation work. The importance of higher-order effects such as reorientation, is demonstrated. 相似文献
7.
Z. B. Alfassi J. P. F. Sellschop 《Journal of Radioanalytical and Nuclear Chemistry》1989,135(5):341-348
Simultaneous determination of boron and lithium is done by double irradiation with protons. One irradiation with 1.55 MeV protons and another with 7.4 MeV protons, measuring in both cases the amount of7Be formed /7Li/p,n/7Be and10B/p,/7Be/. Deuteron bombardment was not found to be of much advantage. 相似文献
8.
Angular distributions have been measured at energies near the Coulomb barrier for the systems 18O + 24Mg, 12C + 28Si and 16, 18O + 28Si for elastic scattering and inelastic scattering to the first 2+ states in 18O, 24Mg and 28Si. Coupled-channel calculations were required in order to reproduce the details of the strong Coulomb-nuclear interference minima. However, a satisfactory account of the main features of the data was obtained in a first-order DWBA analysis and with the closed formalism of Frahn. With the exception of 18O, it was sufficient to assume equal charge and optical-potential deformation lengths. 相似文献
9.
K. Bharuth‐Ram R. Scheuermann I.Z. Machi S.H. Connell J. Major J.P.F. Sellschop A. Seeger 《Hyperfine Interactions》1997,105(1-4):339-344
Transverse‐field μSR spectroscopy was used to study the behaviour of positive muons implanted in polycrystalline chemical‐vapour‐deposited
(CVD) diamond. Measurements were made at sample temperatures of 10 K, 100 K, and 300 K at a magnetic field of 7.5 mT to study
the behaviour of the “normal” (isotropic) muonium state (MuT) and the diamagnetic states (μd), and at 10 K and 300 K at the so‐called “magic field” of 407.25 mT to study the anomalous (bond‐centred) muonium state (MuBC) and μd. The absolute fractions of the muonium states in the CVD diamond are observed to be close to those in high‐quality natural
type‐IIa single crystal diamond.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
C. S. Erasmus H. W. Fesq E. J. D. Kable S. E. Rasmussen J. P. F. Sellschop 《Journal of Radioanalytical and Nuclear Chemistry》1977,39(1-2):323-334
The NIMROC reference materials NIM-D, NIM-G, NIM-L, NIM-N, NIM-P, and NIM-S and the precious metal ore PTO-1 have been analysed
using thermal and epithermal methods of instrumental neutron activation. The abundances of 40 major, minor and trace elements
are reported. The usefulness of the NIMROC reference materials is assessed in terms of the requirements of neutron activation
techniques. Of the seven reference materials, NIM-L is the most useful geochemical material for activation analysis. It contains
suitably high concentrations of most elements that can be determined. Inhomogeneity problems encountered in PTO-1 for some
elements give emphasis to the difficulty of selecting suitable geological material for ultra-trace elements where small quantities
of sample are used. 相似文献