Sulfur 1<i>s</i> near edge x-ray absorption fine structure spectroscopy of thiophenic and aromatic thioether compounds

Behyan, Shirin; Hu, Yongfeng; Urquhart, Stephen G.

doi:10.1063/1.4807604

Cited by 13 publications

(16 citation statements)

References 78 publications

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“…Behyan et al attribute the two main features of the spectrum to be 1s → σ*(SC)/π*(CC) transitions. The spectrum reported by Behyan et al 36 for neat liquid diphenyl sulfide is similar to that of diphenyl sulfide in toluene solution reported here (Figure 1), setting aside distortion due to fluorescence self-absorption, and differences in energy calibration. Behyan et al discuss the possibility that different conformers might contribute to the liquid spectra, 36 and in particular an all-planar conformation with phenyl and sulfur colocated in one plane.…”

Section: Resultssupporting

confidence: 86%

“…As noted above, we predict that the vapor-phase and solution XAS of diphenyl sulfide ought to be very similar. This is in contrast to previous reports of a remarkably different spectrum for vapor-phase diphenyl sulfide, with the main absorption shifted to lower energy by ∼0.4 eV and lacking a pronounced high-energy peak . We therefore measured the vapor-phase spectrum of diphenyl sulfide, a comparison of which with the liquid-phase toluene solution spectrum is shown in Figure .…”

Section: Resultsmentioning

confidence: 57%

“…This is in contrast to previous reports of a remarkably different spectrum for vapor-phase diphenyl sulfide, with the main absorption shifted to lower energy by ∼0.4 eV and lacking a pronounced high-energy peak. 36 We therefore measured the vapor-phase spectrum of diphenyl sulfide, a comparison of which with the liquid-phase toluene solution spectrum is shown in Figure 6. Our vapor-phase measurements employed diphenyl sulfide evaporated and dispersed in helium gas measured under continuous flow conditions in a gas cell, whereas Behyan et al 36 used low pressures (ca.…”

Section: Resultsmentioning

confidence: 99%

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Sulfur K-Edge X-ray Absorption Spectroscopy of Aryl and Aryl–Alkyl Sulfides

et al. 2019

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Aryl and mixed aryl−alkyl organic sulfides are important species in a variety of fields, including the drug and food industries. They also are present in fossil fuels, where they contribute to the range of sulfur compounds that must be removed by the fuel industry. We have used sulfur K-edge X-ray absorption spectroscopy, in combination with density functional theory calculations, to study the aryl sulfide diphenyl sulfide and two different aryl−alkyl sulfides. The sulfur K near-edge X-ray absorption spectra are strongly affected by the coordination of the phenyl ring and are distinct from spectra of the alkyl sulfides. For diphenyl sulfide the spectra are predicted to be sensitive to rotation about the S−C bonds, with experimental spectra corresponding to a sum of thermally accessible conformations. We also have investigated the vapor-phase spectrum of diphenyl sulfide, which is found to be very similar to that of toluene solutions of the compound.

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

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Sulfur K-Edge X-ray Absorption Spectroscopy of Aryl and Aryl–Alkyl Sulfides

et al. 2019

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“…Previous studies of thiophene near-edge spectra 40,43,44 reported intense features at the edge corresponding to low-lying transitions that have been assigned as 1s → (S–C)π* and 1s → (S–C)σ*, with the former at slightly lower X-ray energy. In order to confirm these assignments we first studied single crystal polarized spectra of thiophene-3-carboxylic acid.…”

Section: Resultsmentioning

confidence: 99%

Long-Range Chemical Sensitivity in the Sulfur K-Edge X-ray Absorption Spectra of Substituted Thiophenes

et al. 2014

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Thiophenes are the simplest aromatic sulfur-containing compounds and are stable and widespread in fossil fuels. Regulation of sulfur levels in fuels and emissions has become and continues to be ever more stringent as part of governments’ efforts to address negative environmental impacts of sulfur dioxide. In turn, more effective removal methods are continually being sought. In a chemical sense, thiophenes are somewhat obdurate and hence their removal from fossil fuels poses problems for the industrial chemist. Sulfur K-edge X-ray absorption spectroscopy provides key information on thiophenic components in fuels. Here we present a systematic study of the spectroscopic sensitivity to chemical modifications of the thiophene system. We conclude that while the utility of sulfur K-edge X-ray absorption spectra in understanding the chemical composition of sulfur-containing fossil fuels has already been demonstrated, care must be exercised in interpreting these spectra because the assumption of an invariant spectrum for thiophenic forms may not always be valid.

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“…[23][24][25] The specificity of NEXAFS spectroscopy renders it an attractive technique for investigating elements that are essentially silent by NMR spectroscopy, for example, sulfur. [26][27][28][29] NEXAFS spectroscopy involves the study of the absorption of an X-ray photon by the element of interest, leading to promotion of an electron from a core orbital to a previously unoccupied molecular orbital (UMO). Absorption is generally indirectly monitored by measurement of either the fluorescence yield (FY) or the electron yield (EY), e.g.…”

Section: Introductionmentioning

confidence: 99%

NEXAFS spectroscopy of ionic liquids: experiments versus calculations

Fogarty

Matthews

Clough

et al. 2017

Phys. Chem. Chem. Phys.

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Experimental near edge X-ray absorption fine structure (NEXAFS) spectra are reported for 12 ionic liquids (ILs) encompassing a range of chemical structures for both the sulfur 1s and nitrogen 1s edges and compared with time-dependent density functional theory (TD-DFT) calculations. The energy scales for the experimental data were carefully calibrated against literature data. Gas phase calculations were performed on lone ions, ion pairs and ion pair dimers, with a wide range of ion pair conformers considered. For the first time, it is demonstrated that TD-DFT is a suitable method for simulating NEXAFS spectra of ILs, although the number of ions included in the calculations and their conformations are important considerations. For most of the ILs studied, calculations on lone ions in the gas phase were sufficient to successfully reproduce the experimental NEXAFS spectra. However, for certain ILs - for example, those containing a protic ammonium cation - calculations on ion pairs were required to obtain a good agreement with experimental spectra. Furthermore, significant conformational dependence was observed for the protic ammonium ILs, providing insight into the predominant liquid phase cation-anion interactions. Among the 12 investigated ILs, we find that four have an excited state that is delocalised across both the cation and the anion, which has implications for any process that depends on the excited state, for example, radiolysis. Considering the collective experimental and theoretical data, we recommend that ion pairs should be the minimum number of ions used for the calculation of NEXAFS spectra of ILs.

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Sulfur 1s near edge x-ray absorption fine structure spectroscopy of thiophenic and aromatic thioether compounds

Cited by 13 publications

References 78 publications

Sulfur K-Edge X-ray Absorption Spectroscopy of Aryl and Aryl–Alkyl Sulfides

Sulfur K-Edge X-ray Absorption Spectroscopy of Aryl and Aryl–Alkyl Sulfides

Long-Range Chemical Sensitivity in the Sulfur K-Edge X-ray Absorption Spectra of Substituted Thiophenes

NEXAFS spectroscopy of ionic liquids: experiments versus calculations

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