A Study of Cathodoluminescence and Trace Element Compositional Zoning in Natural Quartz from Volcanic Rocks: Mapping Titanium Content in Quartz

Leeman, William P.; MacRae, Colin M.; Wilson, Nick; Torpy, Aaron; Lee, Cin-Ty A.; Student, James J.; Thomas, Jay B.; Vicenzi, Edward P.

doi:10.1017/s1431927612013426

Cited by 73 publications

(56 citation statements)

References 70 publications

(149 reference statements)

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“…1). The latter has previously been attributed to Ti 4+ centres [3] and correlates strongly with the Ti concentration determined by the EPMA point measurements (Fig. 1).…”

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confidence: 86%

Determination of Trace Elements in Quartz by Combined EPMA and CL Microspectrometry

et al. 2014

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Quartz eyes from different porphyry deposits were studied by electron probe microanalysis (EPMA) and hyperspectral cathodoluminescence (CL) mapping to determine their origin. These "eyes" are mm-sized crystals, which are commonly referred to as phenocrysts but in many cases may have formed after magma emplacement.Ti concentrations were determined on a JEOL JXA 8500F EPMA at 20 kV accelerating voltage, 200 nA beam current and 20 μm beam diameter, using two spectrometers with PET crystals in parallel and counting for 80 seconds on peak and 40 seconds each on two backgrounds, resulting in a detection limit of 10 ppm at 99% confidence. Further Ti, Al, and Fe measurements were performed on a Cameca SX100 EPMA at 15 kV, 200 nA, 5 μm, with counting times of 300 s for peak and 150 s each for two backgrounds. One LPET crystal was used fo Ti, two TAP for Al, and two LLiF for Fe, leading to detection limits of 12, 7, and 19 ppm respectively. Averages of 3 spots co-located in bands with similar panchromatic CL intensity were used where possible to improve the analytical precision. Due to a known background hole beneath the Ti Ka peak when using PET crystals [1], a blank correction was performed using the ultra pure silica glass Spectrosil 1000 (Saint Gobain). The blank correction was consistent over 17 analysis sessions spanning 15 months with +16 ± 2 ppm Ti, −27 ± 4 ppm Al, and −9 ± 8 ppm Fe. Hot Springs Quartz (Harvard 122838, [2]) yielded long term averages of 2 ± 3 ppm Ti, 34 ± 6 ppm Al, and 5 ± 7 ppm Fe. As trace data for this standard has not been published and concentrations might vary, laser ablation inductively coupled plasma mass spectrometry was employed to determine contents of 1.21 ± 0.01 ppm Ti, 53 ± 9 ppm Al, and <3 ppm Fe, which is in reasonable agreement with the EPMA data. Although light microscopy and CL indicate damage to the quartz during EPMA at these conditions, comparative measurements of quartz with higher trace content at shorter acquisition times, lower beam current, and larger beam diameter yielded similar results. This implies that even if structural damage to the quartz lattice occurs, Ti, Al, and Fe are not significantly mobilised in the process.Hyperspectral CL maps were collected on the same JEOL instrument with an Ocean Optics QE65000 grating CCD spectrometer at 20 kV, 40 nA, 1 μm, dwell time 40 ms, and stage step size 2 μm. Deconvolution of the CL spectra using the Chimage software revealed three peaks responsible for the total CL emission at energies of 1.93 eV, 2.05 eV and 2.72 eV (Fig. 1). The latter has previously been attributed to Ti 4+ centres [3] and correlates strongly with the Ti concentration determined by the EPMA point measurements (Fig. 1). In addition, a negative correlation between the 1.93 eV emission and the Al concentration is observed by CL-EPMA (Fig. 2) and confirmed by Fourier transform infrared microspectroscopy. This CL emission has previously been attributed to non-bridging oxygen hole centre defects

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“…1). The latter has previously been attributed to Ti 4+ centres [3] and correlates strongly with the Ti concentration determined by the EPMA point measurements (Fig. 1).…”

supporting

confidence: 86%

Determination of Trace Elements in Quartz by Combined EPMA and CL Microspectrometry

et al. 2014

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“…Initial Raman analysis had shown a mixture of signals indicating the possibility of different crystallinities of graphite. The SXE spectrometer equipped with a Princeton CCD [1,2] was used to investigate whether different graphite or carbonaceous forms were present while the CL together with trace Ti analysis, was used to determine the maximum heating temperature using the Tin quartz geothermometry [3]. The sample was mounted in a 25mm round, then mechanically polished with a 1µm final lap and to finish the surface, it was ion beam milled at 2kV, 5°, for 10 minutes using a Technoorg Linda model SEM Prep2.…”

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confidence: 99%

Crystallographic Orientation Information by Soft X-Ray Spectroscopy

et al. 2018

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A field emission electron probe microanalyser (FEG-EPMA) equipped with traditional wavelength and energy dispersive spectrometry, together with soft x-ray emission spectroscopy (SXES) and a cathodoluminescence (CL) spectrometer has been used to investigate a geological sample from a Tanzanian deposit containing graphite, quartz and a number of other minerals. One of the aims of this study was to understand the crystallinity of the graphite, as the geology indicated the ore has been subjected to a heating event up to 800°C. At these conditions the carbon should be fully crystalline graphite. Initial Raman analysis had shown a mixture of signals indicating the possibility of different crystallinities of graphite. The SXE spectrometer equipped with a Princeton CCD [1, 2] was used to investigate whether different graphite or carbonaceous forms were present while the CL together with trace Ti analysis, was used to determine the maximum heating temperature using the Tin quartz geothermometry [3]. The sample was mounted in a 25mm round, then mechanically polished with a 1µm final lap and to finish the surface, it was ion beam milled at 2kV, 5°, for 10 minutes using a Technoorg Linda model SEM Prep2. Prior to examination the sample had a 5nm carbon coat applied. Cathodoluminescence maps were spectrally examined and the Ti 4+ CL peak identified and fitted at each pixel and trace Ti levels measured to calibrate the CL levels as described previously.For the SXE investigation the mapping was performed at 10kV, 70nA, 600ms dwell with the SXE spectrometer utilising a 200N grating that was configured to show from 1 st through to 4 th order C Kα reflections. A spectral examination of the C Kα line found that the second order reflection offered the best compromise between resolution and signal-to-noise ratio, Fig. 1. C Kα spectra from across a number of carbon rich grains clearly showed the graphite structure compared to previous spectra [3,4]. By selecting several energy regions across the C Kα peak and projecting these across the mapped area, Fig. 3, the grains are seen to be composed of graphite with different orientations. Using a scatter plot of the energy regions 260-272eV vs. 280-284eV and selecting the end-member clusters the C Kα spectra are shown in Fig 3. The C Kα is generated by an electron transition from a 2p orbital to an unfilled 1s orbital and theoretical electronic density of states (DOS) calculations by Srbinovsky et al. [5] have shown that the 1s DOS contains no structure while the 2p atomic orbitals do have structure therefore the 2p DOS reflect the shape of the C Kα emission spectra. This study showed that graphite is composed of two distinct spectroscopic forms the 2p(x, y) -1s and the 2pz -1s (Fig 4.). The theoretical spectral shapes are good agreement with C Kα spectra measured using SXE spectrometer [6].

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“…Since the mid-1980s, panchromatic CL imaging (collecting and detecting luminescence without recourse to dispersion or filtering) has been widely used to visualize U/Pb segregation and zonation within zircon grains for accurate isotope concentration measurements made using ion probe measurements for geochronology [2]. More recently, quantification of titanium trace element concentrations below 100 ppm in quartz has been enabled by color CL and spectrum-imaging approaches for thermobarometry purposes [3].With the growth in the optoelectronics market, spectrally resolved CL gained great popularity. The most favored and successful approach involves direct optical coupling between a specimen, a monochromator, and finally a photo-detector (photomultiplier tube or charge coupled device).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Advances in (and a Brief History of) Cathodoluminescence Microscopy

Stowe¹,

Bertilson²,

Hunt³

2017

Microsc Microanal

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Cathodoluminescence (CL) microscopy utilizes the emission of light from a material upon interaction with an electron. Luminescence in the ranges from ultraviolet to infrared wavelengths and may be analysed spatially, spectrally and temporally to form images, spectra and spectrum-images (where each pixel in a data set contains a full spectrum). CL performed in a scanning or scanning transmission electron microscope (SEM or STEM) benefits from the fact that, in these instruments, an electron beam can be made arbitrarily small compared to the (often) nanometer scale mechanism(s) driving the optical behaviours of materials. Furthermore, direct correlation with morphology, microstructure, composition and chemistry using other analytical techniques available in the electron microscope make CL a very attractive characterization tool. Here we will review the astonishing progress made recently using the CL technique from quantification of trace impurities, revealing the local density of optical states in metallic nanoparticles far below the optical diffraction limit to the study of individual quantum emitters and look forward to the exciting research possibilities in the near future.The phenomena of cathodoluminescence was first reported in 1879 by Crooks who examined the bluegreen light emitted from synthetic calcium sulfide crystals bombarded with a cathode ray [1]. However, it wasn't until the advent of its use in petrographic studies in the 1960s and 1970s that CL found widespread application where CL imaging and spectroscopy were used for the reconstruction of processes of mineral formation and alteration by the visualization of growth textures. Since the mid-1980s, panchromatic CL imaging (collecting and detecting luminescence without recourse to dispersion or filtering) has been widely used to visualize U/Pb segregation and zonation within zircon grains for accurate isotope concentration measurements made using ion probe measurements for geochronology [2]. More recently, quantification of titanium trace element concentrations below 100 ppm in quartz has been enabled by color CL and spectrum-imaging approaches for thermobarometry purposes [3].With the growth in the optoelectronics market, spectrally resolved CL gained great popularity. The most favored and successful approach involves direct optical coupling between a specimen, a monochromator, and finally a photo-detector (photomultiplier tube or charge coupled device). CL has been used extensively to analyse point and extended defects in bulk compound semiconductors and nanostructures e.g. [4] and [5] and recently to elucidate the local density of optical states in metallic nanoparticles with analysis modalities now including angularly resolved CL [6]. The strong interest in developing light emitting diodes emitting at deep ultraviolet wavelengths (<250 nm) for water purification applications and the expansion in narrow bandgap semiconductors for mid-and long-wavelength infrared detectors (3 -10 µm) has seen the development of spectrally resolved CL systems free ...

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A Study of Cathodoluminescence and Trace Element Compositional Zoning in Natural Quartz from Volcanic Rocks: Mapping Titanium Content in Quartz

Cited by 73 publications

References 70 publications

Determination of Trace Elements in Quartz by Combined EPMA and CL Microspectrometry

Determination of Trace Elements in Quartz by Combined EPMA and CL Microspectrometry

Crystallographic Orientation Information by Soft X-Ray Spectroscopy

Advances in (and a Brief History of) Cathodoluminescence Microscopy

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