Soft X-ray and cathodoluminescence measurement, optimisation and analysis at liquid nitrogen temperatures

MacRae, Colin M.; Wilson, Nicholas C.; Torpy, Aaron; Piane, Claudio Delle

doi:10.1088/1757-899x/304/1/012010

Cited by 5 publications

(5 citation statements)

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“…The energy range of the SXES using the 50XL grating was 45–153 eV. In these experiments, the energy scale was calibrated using higher-order carbon K α reflections from graphite (MacRae et al, 2018 a ).…”

Section: Methodsmentioning

confidence: 99%

“…Electron energy loss spectroscopy (EELS) is readily used to detect exceedingly small energy losses from transmitted electrons in thin films, where these losses can be attributed to low energy ionization events (Egerton, 2013). Alternatively, soft X-ray emission spectroscopy (SXES) in transmission electron microscopy or electron probe micro-analysis (EPMA) is capable of detecting X-rays emitted within the soft X-ray range, 10 eV to 2 keV (Terauchi et al, 2010), through methods similar to wavelength-dispersive spectroscopy (Kita et al, 1983; Terauchi & Kawana, 2006; Takahashi et al, 2016; MacRae et al, 2018 a ). A curved grating is used to diffract the incoming X-rays, which are then sent to and recorded by a CCD camera to obtain an energy spectrum (Terauchi & Kawana, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…A curved grating is used to diffract the incoming X-rays, which are then sent to and recorded by a CCD camera to obtain an energy spectrum (Terauchi & Kawana, 2006). The resolution of these systems varies across the energy range and typically ranges from 100 meV to 10 eV, allowing them to resolve X-ray emission lines and their higher-order reflections within the soft X-ray range (Takahashi et al, 2016; MacRae et al, 2018 a ). With these new capabilities, simulations must be tailored to the application of low-energy excitations, and this begins with accurate MACs, ionization cross-sections, fluorescence yields, transition rates, and Coster–Kronig parameters (Heinrich & Newbury, 1991).…”

Section: Introductionmentioning

confidence: 99%

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The Impact of Chemical Bonding on Mass Absorption Coefficients of Soft X-rays

et al. 2020

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Accurate elemental quantification of materials by X-ray detection techniques in electron microscopes or microprobes can only be carried out if the appropriate mass absorption coefficients (MACs) are known. With continuous advancements in experimental techniques, databases of MACs must be expanded in order to account for new detection limits. Soft X-ray emission spectroscopy (SXES) is a characterization technique that can detect emitted X-rays whose energies are in the range of 10 eV to 2 keV by using a varied-line-spaced grating. Transitions producing soft X-rays can be detected and accurate MACs are required for use in quantification. This work uses Monte Carlo modeling coupled with multivoltage SXES measurements in an electron probe micro-analyzer (EPMA) to compute MACs for the L2,3-M and Li Kα transitions in a variety of aluminum alloys. Electron depth distribution curves obtained by the software MC X-ray are used in a parametrized fitting equation. The MACs are calculated using a least-squares regression analysis. It is shown that X-ray distribution cross-sections at such low energies need to take into account additional contributions, such as Coster–Kronig transitions, Auger yields, and wave function effects in order to be accurate.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Impact of Chemical Bonding on Mass Absorption Coefficients of Soft X-rays

et al. 2020

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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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“…The detection of several low energy N line emissions have now been demonstrated and Ce and La N emissions used for mapping 5-50 nm structures [7]. Li K is at the low energy limit and although obtaining a Li peak from pure metal is comparatively straightforward, some Li compounds dissociate under the beam [8]. Dissociation and migration of Li with formation of surface Li particles has also been seen in LiLaAlZr oxide electrolyte after exposure to a 500pA 5kV beam for 5 minutes [9].…”

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confidence: 99%

Material Discrimination at High Spatial Resolution using Sub-300eV X-rays

et al. 2018

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Oxford Instruments NanoAnalysis, High Wycombe, Bucks, U.K.Conventional X-ray analysis has relied on X-rays being generated by transitions that produce X-rays at a fixed energy characteristic of the atom involved and where the generated intensity from a bulk material is proportional to the mass fraction of the element. In the decades that followed Castaing's pioneering work on quantitative microprobe analysis with a wavelength dispersive spectrometer (WDS), many research groups worked on improving the algorithms for correcting for the effects of the matrix on excitation and absorption, the technology for the energy dispersive spectrometer (EDS) improved and there is now international consensus on how reliable element compositional analysis for atomic number Z>=11 can be achieved with EDS at beam energies of 10-25keV [1]. For X-ray energies below 1 keV, quantitative analysis using L and M line emissions is less reliable because of anomalous absorption and chemical bonding effects [2] and at energies below 300 eV, the chemical environment of the atom has a significant influence even on K emissions. Such "chemical effects" were seen as a barrier to quantitative analysis and were the subject of considerable investigation in the 1960's (e.g. [3]). At the time, special purpose instruments were built for particular research projects and used electron beams that were not capable of high spatial resolution.Quantitative analysis for sub-300eV X-rays still remains an elusive goal except for some restricted areas of application. However, in the last few years, some major technology advances have enabled new spectrometers to become available commercially that offer detection of X-rays to below 50 eV in energy ("SXES" WDS [4] and "X-Max Extreme" EDS [5]) and can be mounted on electron columns that can provide high beam currents at low kV with a highly focussed beam. This has allowed investigators to discover new ways to characterise materials that are beyond the bounds of conventional microanalysis. SXES provides extremely good energy resolution (0.2 eV) revealing the full emission profile and has enabled collection of new data that surpasses what was discovered in the 1960's. X-max Extreme resolution approaches 30 eV fwhm at these energies but is much more sensitive so that good signals can be obtained at much smaller beam currents and considerably faster than SXES. Chemical state is impossible to determine from X-ray intensity alone but the shape of the X-ray emission profile can sometimes enable discrimination of materials in different chemical and crystallographic states. Figure 1 shows two spectra taken from graphite facets of different orientation that show shifts in C Kα position consistent with the variation in shoulder due to p bonding that has been shown by SXES [4]. However emission band changes in Si L between pure Si and TiSi2 and in B K between CaB6 and LaB6 that are detectable by SXES [6] are too subtle to be discriminated using X-max Extreme. Furthermore energy shifts between different chemical states can be v...

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Soft X-ray and cathodoluminescence measurement, optimisation and analysis at liquid nitrogen temperatures

Cited by 5 publications

References 29 publications

The Impact of Chemical Bonding on Mass Absorption Coefficients of Soft X-rays

The Impact of Chemical Bonding on Mass Absorption Coefficients of Soft X-rays

Crystallographic Orientation Information by Soft X-Ray Spectroscopy

Material Discrimination at High Spatial Resolution using Sub-300eV X-rays

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