Calculations of the X-ray absorption edge form of disordered carbon-contained compounds

Kolpachev, A. B.; Bazhin, I. V.; Nikiforov, I. Ya.

doi:10.1016/0921-4526(94)01032-v

Cited by 2 publications

(2 citation statements)

References 6 publications

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“…For instance, XANES data allow documenting the aromatization of organic compounds during thermal maturation. ,, However, in contrast to what can be achieved using nuclear magnetic resonance (NMR) spectroscopy on large amounts of materials, ,− truly quantitative estimations of functional group concentration from XANES data collected on submicrometric particles has up to now remained out of reach, notably because of the complexity of the physical absorption processes. Theoretical ab initio calculations have aimed at simulating absorption spectra, but while the main features could be identified, calculations fail to reproduce experimental data, notably because of core-hole effects, secondary absorptions, multiple scattering, and convolution with the monochromator, lenses, and detectors of the instrument. − It thus cannot be used for direct quantification purposes. We report a new analytical method to quantitatively assess the molecular composition of carbon materials, i.e.…”

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confidence: 99%

XANES-Based Quantification of Carbon Functional Group Concentrations

et al. 2018

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X-ray absorption spectroscopy in the soft X-ray range is used in many research fields to identify the nature of functional groups in organic compounds and carbon materials. However, the concentrations of these functional groups have so far remained difficult to quantify. Using X-ray absorption near edge structure (XANES) spectra of reference materials (polymers and compounds of known molecular composition), we established a correlation between measured optical densities and functional groups concentration. This methodology relies on an alternative method for normalization to the total amount of carbon and for deconvolution of the spectra. It allows precisely quantifying the N/C atomic ratio (σ1 = 0.02 atom %) as well as the concentration of [aromatic + olefinic] groups (σ1 = 3.7 atom %), [ketone + phenol + nitrile] groups (σ1 = 2.2 atom %), [aliphatic] groups (σ1 = 11.2 atom %) and [carboxylic] groups (σ1 = 7.4 atom %). We validated this quantification by comparing with nuclear magnetic resonance data obtained on pyrolized lignin samples. We also provide an easy-to-use python program automating XANES-based quantification of carbon functional group concentrations.

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XANES-Based Quantification of Carbon Functional Group Concentrations

et al. 2018

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“…In Table 2 the results of the calculations of (Fig. 3 ) , because they do not differ significantly from those found before [14,15] with the same method. The energy distance between the maxima B and C does not change when one goes from T i c to the ternary system but the energy difference of the A and 3 peaks increases by 3 eV.…”

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confidence: 77%

Electronic Energy Structure of the Ternary Carbide System TiAlC

Ilyasov

Nikiforov

Ilyasov

1996

Physica Status Solidi (b)

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With the coherent potential method of the multiple scattering theory the electronic structure of the ternary carbide system Til-,Al,C (z = 0.17) is calculated. The cluster approximation with muffintin crystal potential is used. With the same method the electronic structure of the binary T i c system has been calculated for comparison. It was found that Til-,Al,C (z = 0.17) can be considered as a semiconductor with a narrow energy gap (2.18 eV). Aluminium doping results in an increase of the valence band width and a decrease of the cohesive energy.

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Calculations of the X-ray absorption edge form of disordered carbon-contained compounds

Cited by 2 publications

References 6 publications

XANES-Based Quantification of Carbon Functional Group Concentrations

XANES-Based Quantification of Carbon Functional Group Concentrations

Electronic Energy Structure of the Ternary Carbide System TiAlC

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