نتایج جستجو برای: isotopic
تعداد نتایج: 18280 فیلتر نتایج به سال:
The determination of isotopic ratios by Resonance Ionization Mass Spectrometry (RIMS) requires a thorough characterisation of laser induced isotope effects. Besides the widely discussed odd-even effects (Fairbanks et al.l989,Lambropoulos et al.1989, Payne et al. 1991, Wunderlich et al 1992 a,b) there have also been reports of laser induced shifts in even-even isotopic ratios (Joung et al., 1990...
Absolute values have been obtained for the isotopic abundance ratios of a reference sample of nickel (Standard Reference Material 986), using thermal ionization mass spectrometry. Samples of known isotopic composition, prepared from nearly isotopically pure separated nickel isotopes, were used to calibrate the mass spectrometers. The resulting absolute isotopic ratios are: 58Ni/60Ni=2.596061±0....
Isotopic analysis is of paramount importance across the entire gamut of scientific research. To advance the frontiers of knowledge, a technique for nanoscale isotopic analysis is indispensable. Secondary Ion Mass Spectrometry (SIMS) is a well-established technique for analyzing isotopes, but its spatial-resolution is fundamentally limited. Transmission Electron Microscopy (TEM) is a well-known ...
We use the considered axial deformed relativistic mean field theory to perform system-atical calculations for Z = 112 and 104 isotopic chains with force parameters NL3, NL-SH and NL-Z2 sets. Three deformed chains (oblate, moderate prolate and super-deformed chain) are found for Z = 112 and 104 isotopic chains. It is found that there is a chain of super-deformed nuclei which can increase the sta...
Phonon linewidths can exhibit a large variation when either pressure or isotopic masses are changed. These effects yield detailed information about the mechanisms responsible for linewidths and lifetimes, e.g., anharmonicity or isotopic disorder. We report Raman measurements of the linewidth of the upper E2 phonons of ZnO crystals with several isotopic compositions and their dependence on press...
Introduction: Examining the record contained within the organic matter in meteorites can reveal the nature of the inputs and processes that contributed to the early solar system environment. Specifically, isotopic measurements for individual organic compounds can reveal the reaction mechanisms and possible source environments from which the organic constituents were formed. Hydrogen isotopic me...
To constrain further the Mg isotopic composition of the Earth and chondrites, and investigate the behavior of Mg isotopes during planetary formation and magmatic processes, we report high-precision (±0.06& on dMg and ±0.07& on dMg, 2SD) analyses of Mg isotopes for (1) 47 mid-ocean ridge basalts covering global major ridge segments and spanning a broad range in latitudes, geochemical and radioge...
Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of "non-traditional" isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in term...
This special issue is based on a theme session convened at the Annual Meeting of the Geological Society of America held in Denver, Colorado, in October 2004. The theme session brought together a diverse group of scientists interested in the chemistry of Precambrian and Paleozoic oceans and its role in climatic and evolutionary events. The contributors to this issue make use of a wide range of i...
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