XPS determination of the thickness of adsorbed mouthrinse components on dental enamel

Busscher, Hj; Vandermei, Hc; Genet, Mj.; Perdok, J. F.; Rouxhet, Paul

doi:10.1002/sia.740150508

Cited by 14 publications

(7 citation statements)

References 11 publications

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“…With a nonmonochromatic source, secondary electrons generated at the X‐ray tube window and metal surfaces in the vicinity of the sample stabilize the positive charge developed on the sample surface. In this case, the charging voltage may differ according to the surface composition, as it is influenced by the flux of photoelectrons and thus by the cross‐section of the elements . With a monochromatized X‐ray beam, a specific accessory is used to overcompensate sample charging, making the surface potential negative but hopefully uniform and constant.…”

Section: From Elements To Chemical Functionssupporting

confidence: 76%

XPS analysis of bio‐organic systems

Rouxhet

Genet

2011

Surface & Interface Analysis

265

173

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A survey of the literature is made for the XPS analysis of food products (mainly spray-dried powders, which reveal a considerable surface enrichment in lipids) and of microorganisms and related systems (extracellular polymer substances and biofilms). This survey is used as a background for discussions and recommendations regarding methodology. Sample preparation methods reviewed are freeze drying, analysis of frozen hydrated specimens and adsorption of surface-active biocompounds on model substrates. Peak decomposition is a way to increase the wealth of information provided by the XPS spectra. It should be performed after a check that sample charge stabilization is satisfactory. Moreover, ensuring the precision needed to make comparisons within sets of samples may involve a trade-off between imposing constraints and generating information. The examination of correlations between spectral data in the light of chemical guidelines is useful to validate or improve peak decomposition and component assignment, and may also upgrade the chemical information regarding speciation. Further upgrading may be achieved by expressing marker XPS data in terms of concentrations of compounds of interest. Different methods of computation are discussed, providing a composition in terms of ingredients, classes of biochemical compounds, or various organic and inorganic compounds. As an alternative or complement to this deterministic approach, multivariate analysis of suitable spectral windows provides spectral components, which may be used for comparing samples, and which may have a direct chemical relevance or be used to identify features of interest.

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Section: From Elements To Chemical Functionssupporting

confidence: 76%

XPS analysis of bio‐organic systems

Rouxhet

Genet

2011

Surface & Interface Analysis

265

173

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“…There, one could see a correlation between the evolution of the C surface concentration and the evolution of the spread between the BE of the C (C,H) component of the C 1s peak and the BE of the constitutive elements of the inorganic substrate (Si 2p, Al 2p, O 1s). Even if both the X‐ray energy source and the operating parameters of the charge stabilization devices are maintained constant (which is the case for both spectrometers), the charging term can still be influenced by the total count of the photoelectrons emitted 20. The latter is logically affected by the thickness of the carbon overlayer.…”

Section: Resultsmentioning

confidence: 99%

Calibration of the X‐Ray Photoelectron Spectroscopy Binding Energy Scale for the Characterization of Heterogeneous Catalysts: Is Everything Really under Control?

et al. 2013

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Investigations of X-ray photoelectron spectra from solid samples need corrections for the surface charging effect. For powder samples such as heterogeneous catalysts and their supports, the C(C,H) component of the C 1s peak is often used as an internal standard for the calibration of the binding energy scale. Although this method is widely recognized as suitable for the study of heterogeneous catalysts, we show that a significant calibration bias can be encountered upon comparing samples with different bulk composition. In this paper, a series of SiO2 -Al2 O3 supports and Pd/SiO2 -Al2 O3 catalysts with various Si/Al ratios were studied. The spectra issued from these samples were processed with the classical calibration method on the basis of the carbon peak. Important discrepancies in the relative position of the photoelectron peaks were noticed. After systematically discarding instrument-related issues, a true chemical influence of the bulk matrix on the analyzed surface specie... Document type : Article de périodique (Journal article) Référence bibliographiqueJacquemin, Marc ; Genet, Michel J. ; Gaigneaux, Eric M. ; Debecker, Damien P.. Calibration of the X-ray photoelectron spectroscopy binding energy scale for the characterization of heterogeneous catalysts: is everything really under control?.

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“…A correlation between charging shift of substances adsorbed on dental enamel and thickness of adsorbed layer was observed and tentatively attributed to a variation of photoemitted electron Ñux. 29 Overlayer charging, like substrate charging, is probably determined by the balance of electron Ñuxes in the phase considered, which involves the photoemitted Ñux, the Ñood gun electrons Ñux and also the Ñux of electrons from the substrate to the overlayer. Figure 6 shows that, according to the assigned binding energy, the charging shift is the same for the PDMS overlayer as for NaCl substrate.…”

Section: Overlayermentioning

confidence: 99%

Surface charging of insulating samples in x‐ray photoelectron spectroscopy

Vereecke¹,

Rouxhet²

1998

Surf. Interface Anal.

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Electrical charging of insulating samples during XPS is of direct concern for referencing the binding energy scale. Results are presented on charging of composite insulating samples that consist of an organic overlayer of polystyrene (PS) or polydimethylsiloxane (PDMS) deposited on NaCl particles. The samples were analysed using small-spot monochromatized radiation, the surface charge being stabilized with an electron Ñood gun. The charging shift of the NaCl substrate is inÑuenced by three di †erent factors : the total photoelectron Ñux, the energy of the electrons produced by the Ñood gun and the Ñux of electrons originating from the overlayer. The overlayer is acting as an additional electron source, which makes the substrate more negative and reduces inhomogeneities of the local potential a †ecting the peak full width at half-maximum. Comparison of substrate peak intensities with computed values showed that PS overlayers were less uniform compared to PDMS overlayers. The overlayer thickness and uniformity a †ect both the total photoelectron Ñux and the Ñux of electrons from the overlayer to the substrate. Overlayer charging, like substrate charging, is probably determined by the balance of electron Ñuxes in the phase considered. The kinetic energy of the photoelectron is determined by the electrical potential in the phase where photoemission occurs and not with respect to the sample surface. This was demonstrated by di †erential charging between the NaCl substrate and PS overlayer.

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XPS determination of the thickness of adsorbed mouthrinse components on dental enamel

Cited by 14 publications

References 11 publications

XPS analysis of bio‐organic systems

XPS analysis of bio‐organic systems

Calibration of the X‐Ray Photoelectron Spectroscopy Binding Energy Scale for the Characterization of Heterogeneous Catalysts: Is Everything Really under Control?

Surface charging of insulating samples in x‐ray photoelectron spectroscopy

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