X-ray photoemission studies of diamond, graphite, and glassy carbon valence bands

McFeely, F. R.; Kowalczyk, S. P.; Ley, L.; Cavell, Ronald G.; Pollak, R. A.; Shirley, D. A.

doi:10.1103/physrevb.9.5268

Cited by 541 publications

(161 citation statements)

References 18 publications

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“…The spectra shown have not been corrected or processed apart from a background subtraction. The calibration of our instrument was confirmed by measuring a clean sample of highly oriented pyrolytic graphite, which gives a sharp C 1s peak centered at 284.4 eV and FWHM of 1.2 eV, in good agreement with the literature (30,41). The fitting process, quantitative analysis, and error estimation were performed using the CasaXPS software.…”

Section: Methodsmentioning

confidence: 54%

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Formation and emission of large furans and oxygenated hydrocarbons from flames

Johansson

Dillstrom

Monti

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. We used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that furans are produced in the high-temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ∼100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbonand oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming.furans | oxygenated hydrocarbons | soot | organic carbon | black carbon

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Section: Methodsmentioning

confidence: 54%

“…The abundance of ethers included in soot particles increases with increasing DFFO, suggesting that alcohols/enols are precursors to ethers. The fractions of C-OH, C-O-C, and C=O species at different DFFOs were determined by analysis of the O 1s spectra (30,41) and are shown in Fig. 6D.…”

Section: Resultsmentioning

confidence: 99%

Formation and emission of large furans and oxygenated hydrocarbons from flames

Johansson

Dillstrom

Monti

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Manne [16] has discussed the comparison of x-ray photoemission (XPS) and x-ray emission (XES) spectra. By combining these ideas and applying them to solids, we have been able to deduce the atomic-orbital compositions of diamond and graphite [17]. The diamond case is illustrated in Fig.…”

Section: Insertion Of Experimental Valuesmentioning

confidence: 99%

Esca. results versus other physical and chemical data

Shirley

1974

Journal of Electron Spectroscopy and Related Phenomena

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“…It indicates that the surfaces of Si-DLC films are rich in sp 2 bonded carbon. Another peak at 292.7 eV was attributed to π-excitation, which appears in all carbon compounds having double bonds [27][28][29]. The Si 2p spectrum was deconvoluted into five components with a strong peak for Si-C (Si 1+) bond at 100.7 eV and two small peaks for Si 2 O 3 (Si 3+) and SiO 2 (Si 4+) type of binding at 102.3 eV and 103.4 eV respectively (the number in bracket denotes the oxidation state of Si).…”

Section: X-ray Photoelecron Spectroscopy (Xps) Studiesmentioning

confidence: 99%

“…5 (g)) was deconvoluted into five components at 284.4, 285.1, 286.6, 288.5 and 293.5 eV. These peak positions are assigned to the binding energy of C _ C, C-C, C-O, C _ O bonded network and π-excitation respectively [25][26][27][28][29]45]. The ratio of the C _ C to C-C bonds was similar to that of the untreated Si-DLC film shown in Fig.…”

Section: X-ray Photoelecron Spectroscopy (Xps) Studiesmentioning

confidence: 99%

Surface energy of the plasma treated Si incorporated diamond-like carbon films

Roy

Choi

Park

et al. 2007

Diamond and Related Materials

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Surface energy and surface chemical bonds of the plasma treated Si incorporated diamond-like carbon films (Si-DLC) were investigated. The Si-DLC films were prepared by r.f. plasma assisted chemical vapor deposition using benzene and diluted silane (SiH 4 /H 2 = 10:90) as the precursor gases. The Si-DLC films were subjected to plasma treatment using various gases like N 2 , O 2 , H 2 and CF 4 . The plasma treated Si-DLC films showed a wide range of water contact angles from 13.4°to 92.1°. The surface energies of the plasma treated Si-DLC films revealed a high polar component for O 2 plasma treated Si-DLC films and a low polar component for CF 4 plasma treated Si-DLC films. The CF 4 plasma treated Si-DLC films indicated the minimum surface energy. X-ray photoelectron spectroscopy (XPS) revealed that the polarizability of the bonds present on the surface explains the hydrophilicity and hydrophobicity of the plasma treated Si-DLC films. We also suggest that the O 2 plasma treated surface can provide an excellent hemocompatible surface from the estimated interfacial energy between the plasma treated Si-DLC surface and human blood.

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X-ray photoemission studies of diamond, graphite, and glassy carbon valence bands

Cited by 541 publications

References 18 publications

Formation and emission of large furans and oxygenated hydrocarbons from flames

Formation and emission of large furans and oxygenated hydrocarbons from flames

Esca. results versus other physical and chemical data

Surface energy of the plasma treated Si incorporated diamond-like carbon films

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