Correction of secondary X-ray fluorescence near grain boundaries in electron microprobe analysis: Application to thermobarometry of spinel lherzolites

Llovet, Xavier; Galán, Gumer

doi:10.2138/am-2003-0115

Cited by 75 publications

(27 citation statements)

References 32 publications

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“…Fortunately, photon transport in matter has been modeled with the Monte Carlo program PENELOPE, 5 and has been shown to accurately reproduce secondary fluorescence. 6,7 PENELOPE has the ability to model different accelerating voltages and position a detector at different take-off angles (here we used 40°). The original version of PENELOPE used to acquire data here had one annular detector (with the proper take-off angle), which although physically unrealistic, speeded up computation.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation of Nb Kα secondary fluorescence in EPMA: comparison of PENELOPE simulations with experimental results

Fournelle

Kim

Perepezko

2005

Surface & Interface Analysis

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Secondary fluorescence across phase boundaries is a difficult problem encountered in several electron probe microanalysis (EPMA) situations: diffusion couples; small phases enclosed in a larger phases; eutectic intergrowths; and thin films. In some cases, it is possible to construct nondiffused couples and to measure the amount of secondary fluorescence across the phase boundary, but in most cases this is difficult, time consuming, expensive, or impossible. It is thus desirable to model the secondary fluorescence by Monte Carlo methods. Here we compare the results of experimentally measured secondary fluorescence of Nb K a with results from the PENELOPE Monte Carlo program, and find that there is close correspondence.

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Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation of Nb Kα secondary fluorescence in EPMA: comparison of PENELOPE simulations with experimental results

Fournelle

Kim

Perepezko

2005

Surface & Interface Analysis

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“…Jercinovic et al [10] showed that the accuracy of EPMA decreases at low concentrations because most random and systematic errors encountered during major element analysis are magnified at trace level and specific errors appear. Among the special sources of errors during trace element analysis, the most important are spectral background subtraction, secondary fluorescence from phase boundaries (e.g., [48][49][50]), surface contamination from coating or sample preparation (e.g., [19]) and beam damage caused by high beam current and long counting times [1,10].…”

Section: Figurementioning

confidence: 99%

Trace element analysis by EPMA in geosciences: detection limit, precision and accuracy

Batanova

Sobolev

Magnin

2018

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Use of the electron probe microanalyser (EPMA) for trace element analysis has increased over the last decade, mainly because of improved stability of spectrometers and the electron column when operated at high probe current; development of new large-area crystal monochromators and ultra-high count rate spectrometers; full integration of energy-dispersive / wavelength-dispersive X-ray spectrometry (EDS/WDS) signals; and the development of powerful software packages. For phases that are stable under a dense electron beam, the detection limit and precision can be decreased to the ppm level by using high acceleration voltage and beam current combined with long counting time. Data on 10 elements (Na, Al, P, Ca, Ti, Cr, Mn, Co, Ni, Zn) in olivine obtained on a JEOL JXA-8230 microprobe with tungsten filament show that the detection limit decreases proportionally to the square root of counting time and probe current. For all elements equal or heavier than phosphorus (Z = 15), the detection limit decreases with increasing accelerating voltage. The analytical precision for minor and trace elements analysed in olivine at 25 kV accelerating voltage and 900 nA beam current is 4 -18 ppm (2 standard deviations of repeated measurements of the olivine reference sample) and is similar to the detection limit of corresponding elements. To analyse trace elements accurately requires careful estimation of background, and consideration of sample damage under the beam and secondary fluorescence from phase boundaries. The development and use of matrix reference samples with well-characterised trace elements of interest is important for monitoring and improving of the accuracy. An evaluation of the accuracy of trace element analyses in olivine has been made by comparing EPMA data for new reference samples with data obtained by different in-situ and bulk analytical methods in six different laboratories worldwide. For all elements, the measured concentrations in the olivine reference sample were found to be identical (within internal precision) to reference values, suggesting that achieved precision and accuracy are similar. The spatial resolution of EPMA in a silicate matrix, even at very extreme conditions (accelerating voltage 25 kV), does not exceed 7 -8 µm and thus is still better than laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) or secondary ion mass spectrometry (SIMS) of similar precision. These make the electron microprobe an indispensable method with applications in experimental petrology, geochemistry and cosmochemistry. IntroductionThere is no rigorous definition of a trace element, and typically accepted definitions depend on the field of science. For example, in analytical chemistry, a trace element is one whose concentration is less than 100 parts per million (ppm) or less than 100 micrograms per gram; while in geochemistry, a trace element has a concentration less than 1000 ppm or 0.1 wt% of a rock's mass and substitutes for major elements in the rock-forming minerals. Reed [1] defines a...

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“…Modeling of secondary fluorescence across boundaries between olivine and Ca-containing minerals has been performed by Adams and Bishop (1986) using empirical methods and by Llovet and Galán (2003) using an earlier version of the PENEPMA program. More recently, Goodrich et al (2014) used the computer code FANAL (Llovet et al 2012) to correct for secondary fluorescence effects between silicate minerals (olivine and pyroxene) and Cr-rich mineral phases.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Of course, secondary fluorescence occurs within homogeneous phases also, but this effect is quantitatively accounted for by all standard matrix correction algorithms; it is only when the target is inhomogeneous, such as near a phase boundary, that worrisome artifacts are likely to arise (see e.g. Llovet and Galán, 2003;Wade and Wood, 2012). For example, measurements of Cr concentrations in chromite-hosted mineral or glass inclusions with diameters up to tens of m (Schiano et al, 1998;Spandler et al, 2005;Borisova et al, 2012, Husen et al, 2016 are likely affected by the secondary fluorescence from the chromite host, but this effect has…”

Section: Introductionmentioning

confidence: 99%

Secondary fluorescence effects in microbeam analysis and their impacts on geospeedometry and geothermometry

et al. 2018

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Characteristic and bremsstrahlung x-ray emission during electron-specimen interactions in electron microprobe (EPMA) and scanning electron microscope (SEM) instruments causes secondary fluorescence x-ray effects from adjacent (boundary) phases. This is well-known, yet the impact of such effects in microbeam analysis of natural mineral-hosted inclusions and adjacent to mineral-mineral and mineral-glass boundaries are frequently neglected, especially in geospeedometry and geothermometry applications. To demonstrate the important influence of the secondary fluorescence effect on the measured concentration of elements and its consequences for geochemical applications, we consider the effect of mineral-mineral and mineral-glass boundaries in microanalysis of Cr, Zr and Ti both experimentally, using electron probe measurements on cold-pressed material couples, and computationally, using the software suite "CalcZAF/Standard" and its Graphical User Interface (GUI) for the semianalytical model FANAL (Llovet et al., 2012). We demonstrate, for example, that apparent Cr contents of the order of ~3000 to 5000 ppm in chromite-hosted glass inclusions at 6 m from the inclusion boundary can be entirely due to secondary fluorescence in the Cr-rich host phase. Because the spatial gradient in secondary fluorescence-induced x-ray emission superficially resembles a diffusion profile, we emphasize the need to quantitatively correct for such effects in any geospeedometry application involving measurement of diffusion profiles adjacent to grain boundaries with large concentration contrasts. We also provide a scheme for estimating analytical errors related to the secondary fluorescence effect when applying geothermometers such as Ti-in-zircon, Ti-in-quartz (TitaniQ) and Zr-in-rutile. Temperature estimates based on trace Ti, Zr and Cr contents in minerals and glasses affected by secondary ACCEPTED MANUSCRIPTA C C E P T E D M A N U S C R I P T 3 fluorescence in nearby phases (e.g., rutile, zircon and chromite) can be severely overestimated, in some cases by hundreds of degrees Celsius.

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Correction of secondary X-ray fluorescence near grain boundaries in electron microprobe analysis: Application to thermobarometry of spinel lherzolites

Cited by 75 publications

References 32 publications

Monte Carlo simulation of Nb Kα secondary fluorescence in EPMA: comparison of PENELOPE simulations with experimental results

Monte Carlo simulation of Nb Kα secondary fluorescence in EPMA: comparison of PENELOPE simulations with experimental results

Trace element analysis by EPMA in geosciences: detection limit, precision and accuracy

Secondary fluorescence effects in microbeam analysis and their impacts on geospeedometry and geothermometry

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