The suppression of fluorescence peaks in energy-dispersive X-ray diffraction

Hansford, G. M.; Turner, S. M. R.; Staab, Daniel; Vernon, David T. A.

doi:10.1107/s160057671401927x

Cited by 6 publications

(11 citation statements)

References 44 publications

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“…10 which shows three EDXRD spectra of a limestone rock specimen, recorded at different locations on the same sample, and the spectrum of a pressedpowder pellet made from a portion of the same rock. This limestone contains calcite, dolomite and minor quartz [see Hansford et al (2014), referred to as limestone A in that paper]. The diffraction peaks in the spectrum of the pellet are clearly broader, indicating the introduction of crystallite size and/or lattice strain effects during the pulverization and milling of the rock sample.…”

Section: Microstructural Effects On Peak Widthsmentioning

confidence: 99%

“…It is therefore essentially a reflection-mode, surfaceanalysis XRD method, with typical penetration depths of a few microns. The 2011 paper considered the technique from a theoretical standpoint and with the aid of ray-trace modelling whereas subsequent work proved the claims experimentally (Hansford, 2013) and demonstrated a method to suppress fluorescence peaks in order to uncover overlapped diffraction peaks (Hansford et al, 2014). All published work on this technique to date has focused on essentially low-resolution methods using solid-state X-ray detectors [silicon drift detectors (SDDs) and charge-coupled devices (CCDs)] to provide the energy dispersion.…”

Section: Introductionmentioning

confidence: 99%

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High-resolution X-ray diffraction with no sample preparation

Hansford

Turner

Degryse

et al. 2017

Acta Crystallogr A Found Adv

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It is shown that energy-dispersive X-ray diffraction (EDXRD) implemented in a back-reflection geometry is extremely insensitive to sample morphology and positioning even in a high-resolution configuration. This technique allows highquality X-ray diffraction analysis of samples that have not been prepared and is therefore completely non-destructive. The experimental technique was implemented on beamline B18 at the Diamond Light Source synchrotron in Oxfordshire, UK. The majority of the experiments in this study were performed with pre-characterized geological materials in order to elucidate the characteristics of this novel technique and to develop the analysis methods. Results are presented that demonstrate phase identification, the derivation of precise unitcell parameters and extraction of microstructural information on unprepared rock samples and other sample types. A particular highlight was the identification of a specific polytype of a muscovite in an unprepared mica schist sample, avoiding the time-consuming and difficult preparation steps normally required to make this type of identification. The technique was also demonstrated in application to a small number of fossil and archaeological samples. Back-reflection EDXRD implemented in a high-resolution configuration shows great potential in the crystallographic analysis of cultural heritage artefacts for the purposes of scientific research such as provenancing, as well as contributing to the formulation of conservation strategies. Possibilities for moving the technique from the synchrotron into museums are discussed. The avoidance of the need to extract samples from high-value and rare objects is a highly significant advantage, applicable also in other potential research areas such as palaeontology, and the study of meteorites and planetary materials brought to Earth by sample-return missions.

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Section: Microstructural Effects On Peak Widthsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High-resolution X-ray diffraction with no sample preparation

Hansford

Turner

Degryse

et al. 2017

Acta Crystallogr A Found Adv

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“…The instrument applies energy-dispersive XRD (EDXRD) in a back-reflection geometry which has the unique characteristic of insensitivity to sample morphology (Hansford 2011), opening the possibility of analysis of unprepared samples. This technique has been proven experimentally in a laboratory configuration (Hansford 2013;Hansford et al 2014) and, more recently, the first prototype of a handheld instrument has been produced by modification of a Bruker Tracer handheld X-ray fluorescence (XRF) device. The instrument yields XRF information about the sample in addition to diffraction data.…”

Section: Handheld Xrdmentioning

confidence: 99%

Planetary science and exploration in the deep subsurface: results from the MINAR Program, Boulby Mine, UK

Payler

Biddle

Coates

et al. 2016

International Journal of Astrobiology

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Abstract. The subsurface exploration of other planetary bodies can be used to unravel their geological history and assess their habitability. On Mars in particular, present-day habitable conditions may be restricted to the subsurface. Using a deep subsurface mine, we carried out a program of extraterrestrial analog research -MINAR (MINe Analog Research). MINAR aims to carry out the scientific study of the deep subsurface and test instrumentation designed for planetary surface exploration by investigating deep subsurface geology, whilst establishing the potential this technology has to be transferred into the mining industry. An integrated multi-instrument suite was used to investigate samples of representative evaporite minerals from a subsurface Permian evaporite sequence, in particular to assess mineral and elemental variations which provide small scale regions of enhanced habitability. The instruments used were the Panoramic Camera emulator (AUPE-2), Close-Up Imager (CLUPI), Raman Spectrometer, SPLIT (Small Planetary Linear Impulse Tool), Ultrasonic Drill and handheld XRD. We present science results from the analog research and show that these instruments can be used to investigate in situ the geological context and mineralogical variations of a deep subsurface environment, and thus habitability, from millimeter to meter scales. We also show that these instruments are complementary. For example, the identification of primary evaporite minerals such as NaCl and KCl, which are difficult to detect by portable Raman spectrometers, can be accomplished with XRD. By contrast, Raman is highly effective at locating and detecting mineral inclusions in primary evaporite minerals. MINAR demonstrates the effective use of a deep subsurface environment for planetary instrument development, understanding the habitability of extreme deep subsurface environments on Earth and other planetary bodies, and advancing the use of space technology in economic mining. IntroductionPlanetary analog research involves the investigation of terrestrial environments that are comparable to extraterrestrial environments. These analogs tend to be focused, at a high level, on science, science operations, or technology research and testing, or a combination of these topics (e.g. Dickinson and Rosen 2003;Sarrazin et al. 2005; Cabrol et al. 2007;Pollard et al. 2009; Lim et al. 2011;Abercromby et al. 2013). Analog field settings are used to evaluate scientific instruments of particular relevance to future flight missions in a rugged field setting. These field tests have, for example, ranged from deserts to underwater settings (e.g. Cabrol et al. 2007;Jasiobedzki et al. 2012;Abercromby et al. 2013), and have taken a variety of forms, from testing a single technology to examine its performance in a particular environment (e.g. Skelley et al. 2007), to fully integrated rover tests utilizing a variety of different instruments (e.g. Schenker et al. 2001).One environment that has received less attention for analog research, but which holds a great deal o...

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“…The experimental setup for the results presented in this paper was very similar to those reported by Hansford (2013) and Hansford et al (2014). This setup employs an in-house X-ray tube with a Cu anode and an e2v CCD-22 (Burrows et al, 2005) charge-coupled detector, which has an open-electrode structure for enhanced low-energy quantum efficiency.…”

Section: Experimental Conditionsmentioning

confidence: 82%

“…For some data sets, an attenuating filter was mounted either in the X-ray beam between the source and sample or in front of the CCD; full details are given with the description of each data set. These filters were used in addition to the polyimide/Al filter reported by Hansford et al (2014). The aperture between the source and sample was either 2 or 3 mm in diameter for the data sets reported here.…”

Section: Experimental Conditionsmentioning

confidence: 99%

Phase-targeted X-ray diffraction

Hansford

2016

J Appl Cryst

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A powder X-ray diffraction (XRD) method to enhance the signal of a specific crystalline phase within a mixture is presented for the first time. Specificity to the targeted phase relies on finding coincidences in the ratios of crystal d spacings and the ratios of elemental characteristic X-ray energies. Such coincidences can be exploited so that the two crystal planes diffract through the same scattering angle at two different X-ray energies. An energy-resolving detector placed at the appropriate scattering angle will detect a significantly enhanced signal at these energies if the target mineral or phase is present in the sample. When implemented using high scattering angles, for example 2 > 150 , the method is tolerant to sample morphology and distance on the scale of $2 mm. The principle of the method is demonstrated experimentally using Pd L 1 and Pd L 1 emission lines to enhance the diffraction signal of quartz. Both a pure quartz powder pellet and an unprepared mudstone rock specimen are used to test and develop the phase-targeted method. The technique is further demonstrated in the sensitive detection of retained austenite in steel samples using a combination of In L 1 and Ti K emission lines. For both these examples it is also shown how the use of an attenuating foil, with an absorption edge close to and above the higher-energy characteristic X-ray line, can serve to isolate to some degree the coincidence signals from other fluorescence and diffraction peaks in the detected spectrum. The phase-targeted XRD technique is suitable for implementation using low-cost off-the-shelf components in a handheld or inline instrument format.

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The suppression of fluorescence peaks in energy-dispersive X-ray diffraction

Cited by 6 publications

References 44 publications

High-resolution X-ray diffraction with no sample preparation

High-resolution X-ray diffraction with no sample preparation

Planetary science and exploration in the deep subsurface: results from the MINAR Program, Boulby Mine, UK

Phase-targeted X-ray diffraction

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