Glass surface analysis

Dawson, P.T., Heavens, O.S. and Pollard, A.M. (1978). Glass surface analysis by Auger electron spectroscopy. Journal of Physics C 11 2183-2193. 

Keywords E glass surface analysis silane coupling agent fibre composites. 

XPS has been used in almost every area in which the properties of surfaces are important. The most prominent areas can be deduced from conferences on surface analysis, especially from ECASIA, which is held every two years. These areas are adhesion, biomaterials, catalysis, ceramics and glasses, corrosion, environmental problems, magnetic materials, metals, micro- and optoelectronics, nanomaterials, polymers and composite materials, superconductors, thin films and coatings, and tribology and wear. The contributions to these conferences are also representative of actual surface-analytical problems and studies [2.33 a,b]. A few examples from the areas mentioned above are given below more comprehensive discussions of the applications of XPS are given elsewhere [1.1,1.3-1.9, 2.34—2.39]. 

If the rf source is applied to the analysis of conducting bulk samples its figures of merit are very similar to those of the dc source [4.208]. This is also shown by comparative depth-profile analyses of commercial coatings an steel [4.209, 4.210]. The capability of the rf source is, however, unsurpassed in the analysis of poorly or nonconducting materials, e.g. anodic alumina films [4.211], chemical vapor deposition (CVD)-coated tool steels [4.212], composite materials such as ceramic coated steel [4.213], coated glass surfaces [4.214], and polymer coatings [4.209, 4.215, 4.216]. These coatings are used for automotive body parts and consist of a number of distinct polymer layers on a metallic substrate. The total thickness of the paint layers is typically more than 100 pm. An example of a quantitative depth profile on prepainted metal-coated steel is shown as in Fig. 4.39. 

Tubes are much more sensitive to convection effects than capillaries, but capillaries contain much smaller amounts of solution for analysis. Transport by convection when tubes are used can be accounted for by experimental evaluation. A disadvantage of both methods is the amount of time required for the experiment, which may be hundreds of hours. The investigator must address the possibility of adsorption of the diffusing solute onto the glass surfaces. In addition, the dimensions of the glass capillary must be known with considerable accuracy. 

Application of Equation 2 requires that an estimate of the surface concentration, C0, be made, and that it is assumed not to change as a function of reaction progress. Conceptually this can be considered equal to concentrations of the sorbed alkali on the glass surface and is estimated from the maximum elemental concentrations measured by XPS analysis. The CQ terms for Rb, Cs, and Sr are 1.3x10, 6.5xlO <4, and 9.2X10"4 moles cm-3, respectively. 

The way in which fluoride is taken up by glass-ionomers has been studied using surface analysis techniques. Dynamic secondary ion mass spectroscopy (SIMS) shows that most of the fluoride becomes concentrated in the surface [248]. Its concentration with depth varies as an error function relationship [248]. X-ray photoelectron spectroscopy (XPS) has suggested that fluoride taken up becomes associated with calcium [249]. However, the form of this association is unclear, because calcium fluoride as such is very insoluble, and when added to a fluoride-free glass-ionomer cement, caused no fluoride to be released [234]. It therefore seems unlikely that the calcium-fluoride association results in formation of Cap2, and further research is necessary to determine the precise nature of the calcium-fluoride association, and thus to resolve this paradox. 

F.FI. Jones, B.M. Hutton, P.C. Hadley, A.J. Eccles, T.A. Steele, R.W. Billington, G. J. Pearson, Fluoride uptake by glass ionomer cements A surface analysis approach. Biomaterials 24 (2003) 107-119. 

In starting a residue analysis in foods, the choice of proper vials for sample preparation is very important. Available vials are made of either glass or polymeric materials such as polyethylene, polypropylene, or polytetrafluoroethylene. The choice of the proper material depends strongly on the physicochemical properties of the analyte. For a number of compounds that have the tendency to irreversible adsorption onto glass surfaces, the polymer-based vials are obviously the best choice. However, the surface of the polymer-based vials may contain phthalates or plasticizers that can dissolve in certain solvents and may interfere with the identification of analytes. When using dichloromethane, for example, phthalates may be the reason for the appearance of a series of unexpected peaks in the mass spectra of the samples. Plasticizers, on the other hand, fluoresce and may interfere with the detection of fluorescence analytes. Thus, for handling of troublesome analytes, use of vials made of polytetrafluoroethylene is recommended. This material does not contain any plasticizers or organic acids, can withstand temperatures up to 500 K, and lacks active sites that could adsorb polar compounds on its surface. 

Table III. Melt Glass Surface Area and Size Analysis...

The rubber is used to scrape solid particles from glass surfaces in gravimetric analysis. 

The quantitative compositional surface analysis of the untreated glass fibers using XPS was complicated by the presence of carbon [5]. Nevertheless, the plot in Fig. 1 reveals that the boron concentration on the untreated fiber surfaces did, in fact, increase in proportion to its addition to the glass formulation, while the... 

Heat-cleaned E-glass slide surface. Table 1 shows that the heat-cleaned glass surface is confirmed to be silica-rich because of higher Si and O surface concentrations compared to the bulk analysis obtained by inductively coupled plasma (ICP). This is accommodated by a lower surface calcium concentration. The SIMS results given below demonstrate that a significant proportion of the oxygen is probably present as silanol. 

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