Search results for "Microprobe"
showing 10 items of 57 documents
Exploratory nuclear microprobe data visualisation using 3- and 4-dimensional biological volume rendering tools
2007
Abstract The emergence of Confocal Microscopy (CM) and Atomic Force Microscopy (AFM) as everyday tools in cellular level biology has stimulated development of 3D data visualisation software. Conventional 2-dimensional images of cell (optical) sections obtained in a transmission electron or optical microscopes and more sophisticated multidimensional imaging methods require processing software capable of 3D rendering and mathematically transforming data in 3-, 4-, or more dimensions. The richness of data obtained from the different nuclear microscopy imaging techniques and often parallel information channels (X-ray, secondary electron, Scanning Transmission Ion Microscopy) is often not obviou…
Incomplete retention of radiation damage in zircon from Sri Lanka
2004
A suite of 18 zircon gemstones from placers in the Highland/Southwestern Complex, Sri Lanka, were subjected to a comprehensive study of their radiation damages and ages. The investigation included X-ray diffraction, Raman and PL spectroscopy, electron microprobe, PIXE and HRTEM analysis, as well as (U-Th)/He and SHRIMP U-Th-Pb age determinations. Zircon samples described in this study are virtually homogeneous. They cover the range from slightly metamict to nearly amorphous. Generally concordant U-Th-Pb ages averaging 555 ± 11 Ma were obtained. Late Ordovician zircon (U-Th)/He ages scattering around 443 ± 9 Ma correspond reasonably well with previously determined biotite Rb-Sr ages for rock…
The structural and dielectric properties of the Na0.96Li0.04NbO3ceramics
2007
Ceramic samples Na0.96Li0.04NbO3 were obtained using ceramic technology. The phase and structural analysis, the microstructure, EDS and EPMA, dielectric and hysteresis loops measurements have been performed. The dielectric and hysteresis loops measurements of Na0.96Li0.04NbO3 have been carried out. The dielectric measurements were performed both without and under axial pressure up to 120 MPa. It was shown that Na0.96Li0.04NbO3 ceramics have orthorhombic symmetry at room temperature and undergo a first order phase transition at a temperature of about 570 K. The axial pressure shifts the phase transition temperature and decreases the hysteresis in field-polarisation and field-strain dependenc…
Low temperature measurements by infrared spectroscopy in $CoFe_2O_4$ ceramic
2012
In this paper results of new far-infrared and middle-infrared measurements (wavenumber range of 4000cm-1 - 100cm-1) in the range of the temperature from 300K to 8K of the CoFe2O4 ceramic are presented. The bands positions and their shapes are the same in the wide temperature range. The quality of the sample was investigated by X-ray, EDS and EPMA studies. The CoFe2O4 reveals the cubic structure (Fd-3m) in the temperature range from 85K to 360 K without any traces of distortion. On the current level of knowledge the polycrystalline CoFe2O4 does not exhibit phase transition in the temperature range from 8 K to 300 K.
Zircon M257 - a homogeneous natural reference material for the ion microprobe U-Pb analysis of zircon
2008
We introduce and propose zircon M257 as a future reference material for the determination of zircon U-Pb ages by means of secondary ion mass spectrometry. This light brownish, flawless, cut gemstone specimen from Sri Lanka weighed 5.14 g (25.7 carats). Zircon M257 has TIMS-determined, mean isotopic ratios (2s uncertainties) of 0.09100 ± 0.00003 for 206pb/238U and 0.7392 ± 0.0003 for 207pb/235U. Its 206pb/238U age is 561.3 ± 0.3 Ma (unweighted mean, uncertainty quoted at the 95% confidence level); the U-Pb system is concordant within uncertainty of decay constants. Zircon M257 contains ∼ 840 μg g−1 U (Th/U ∼ 0.27). The material exhibits remarkably low heterogeneity, with a virtual absence of…
The nature of radiohaloes in biotite: Experimental studies and modeling
2001
Several micro-techniques (confocal laser-Raman microprobe, optical absorption micro-spectroscopy, high-resolution transmission electron microscopy, electron microprobe analysis) were employed in the detailed characterization of radiohaloes in biotites from two Variscan rocks from Germany. The studied biotites are intermediate members of the phlogopite-annite series with Mg/Fe 2+ ratios in the range 1.6–1.0. Radiohaloes in biotite resulted from the impact of 4 He cores (α-particles) emitted from actinide-bearing inclusions. Monte Carlo simulations yielded α ( 238 U, 235 U, and 232 Th series) penetration ranges in biotite between 12.5 and 37.3 μm, which are in reasonable agreement with the ob…
Microanalytical methods for in-situ high-resolution analysis of rock varnish at the micrometer to nanometer scale
2015
Abstract A wide range of analytical techniques were used to investigate rock varnish from different locations (Negev, Israel; Knersvlakte, South Africa; Death Valley and Mojave Desert, California): a 200 nm-femtosecond laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS), an electron probe microanalyzer (EPMA), focused ion beam (FIB) slicing, and scanning transmission X-ray microscopy–near edge X-ray absorption fine structure spectroscopy (STXM–NEXAFS). This combination enables comprehensive high-spatial-resolution analysis of rock varnish. Femtosecond LA-ICP-MS and EPMA were used for quantitative determination of element concentrations. In-situ measurements were conducte…
Quantitative Estimation of Major and Trace Elements in Coals of the Benue Trough, Nigeria
2013
The concentrations of major and trace elements in ash residues of coals of the Benue Trough, Nigeria have been determined by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry, respectively. Major and trace element determination in rocks by fusion on an iridium strip heater followed by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry is extended here to coal ash, and the accuracy of the method is evaluated by including an Argonne Premium Coal reference sample in each analysis program. Si and Al are the major elements detected in the coal ashes. An assessment using worldwide concentration ranges of trace elements in coal ash…
Minute co-variations of Sr/Ca ratios and microstructures in the aragonitic shell of Cerastoderma edule (Bivalvia) – Are geochemical variations at the…
2017
Abstract It remains a challenging task to reconstruct water temperatures from Sr/Ca ratios of bivalve shells. Although in many aragonitic species, Sr/Ca is negatively correlated to temperature – which is expected based on abiogenic precipitation experiments, the incorporation of Sr into the shell of bivalves is strongly controlled by physiological processes and occurs away from the predicted thermodynamic equilibrium. Strontium-to-calcium ratios of aragonitic shells remain far below that of the ambient water. Moreover, Sr concentrations vary considerably among shell portions consisting of different microstructures and/or organic content. Values observed at annual growth lines and within the…
Sulfur isotope ratio measurements of individual sulfate particles by NanoSIMS
2008
Abstract The sulfur isotopic compositions of barite (BaSO4), anhydrite (CaSO4), gypsum (CaSO4·2H2O), mascagnite ((NH4)2SO4), thenardite (Na2SO4), boetite (K2SO4), epsomite (MgSO4·7H2O), magnesium sulfate (MgSO4·xH2O) and cysteine (an amino acid) were determined with a Cameca NanoSIMS 50 ion microprobe employing a Cs+ primary ion beam and measuring negative secondary ions. This ion microprobe permits the analysis of sulfur isotope ratios in sulfates on 0.001–0.5 ng of sample material, enabling the analysis of individual S-bearing particles with diameters as small as 500 nm. The grain-to-grain reproducibility of measurements is typically 5‰ (1σ) for micron-sized grains,