The use of overlayer equations in an X-ray photoelectron spectroscopy study of the adsorption of long-chain alcohol molecules on silica surfaces
17 Nov 1994-Colloids and Surfaces A: Physicochemical and Engineering Aspects (Elsevier)-Vol. 92, Iss: 3, pp 277-292
TL;DR: In this paper, a series of long-chain alcohols of differing chain lengths were adsorbed on silica plates, and the authors measured the thickness of the adorbed layer at a constant angle between the surface and the analyser with varying film thickness, or at variable angles with constant film thickness.
About: This article is published in Colloids and Surfaces A: Physicochemical and Engineering Aspects.The article was published on 1994-11-17. It has received 8 citations till now. The article focuses on the topics: Overlayer & X-ray photoelectron spectroscopy.
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TL;DR: The adsorption behaviour of various organic adsorbates on silica surface is reviewed and some natural macromolecules like proteins and nucleic acids are investigated to study the hydrophobic and hydrophilic binding sites of silica.
614 citations
TL;DR: In this paper, the assembly of thin coatings by alternate adsorption of oppositely charged polyelectrolytes was realized on a variety of uncharged standard polymers, such as poly(propylene), poly(styrene), polymethyl methacrylate, and poly(ethylene terephthalate).
Abstract: Different from the conventional use of charged supports, the assembly of thin coatings by alternate adsorption of oppositely charged polyelectrolytes was realized on a variety of uncharged standard polymers, such as poly(propylene), poly(styrene), poly(methyl methacrylate), and poly(ethylene terephthalate). For the multilayer buildup, the polyelectrolyte pair poly(styrenesulfonate)/poly(choline methacrylate) was used. The quality of the coatings was investigated by UV/vis spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), and X-ray photoelectron spectroscopy (XPS). The multilayer deposition on poly(propylene) (PP) and poly(ethylene terephthalate) (PET) was investigated in detail. On polar poly(ethylene terephthalate) supports, the regular growth of multilayer assemblies is evidenced. In contrast, on less polar supports, in particular on PP, the quality of the poly(styrenesulfonate)/poly(choline methacrylate) multilayers is inferior. However, if a hydrophobically modified poly(choline methacrylate) is employed instead, good quality multilayers are obtained even on PP. Thus, by appropriate choice of the polyelectrolytes used, even very hydrophobic and polar substrates become useful for the alternate adsorption technique.
91 citations
TL;DR: In this article, three types of assemblies and several thicknesses are investigated by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), in combination with other characterization techniques (X-Ray Photoelectron Spectroscopy (XPS), X-Ray Reflectivity (XRR) and Atomic Force Microscopy (AFM)).
82 citations
TL;DR: In this paper, the surface topography of arbitrarily rough samples is analyzed by atomic force microscopy to provide a frequency histogram of the local slopes, which is incorporated into a global, multi-element analysis method for interpretation of the observed XPS elemental intensities.
Abstract: Approaches are described for the analysis of XPS signals from samples comprising thin conformal coatings on substrates with non-ideal surface topography. In particular, attention is focused on arbitrarily shaped rough or curved substrates. Relations are derived for the relative x-ray photoelectron intensities emitted from various elements in such non-ideal samples. The surface topography of arbitrarily rough samples is analysed by atomic force microscopy to provide a frequency histogram of the local slopes, which is incorporated into a global, multi-element analysis method for interpretation of the observed XPS elemental intensities. An analogous approach is used for the analysis of curved samples. Our algorithms also enable simultaneous analysis of successively coated multilayer structures. When the elemental composition of the individual layers is known, the fit procedure enables determination of the thickness values of single-layer and multilayer coatings. The range of validity of the theory is discussed. © 1997 by John Wiley & Sons, Ltd.
32 citations
TL;DR: In this paper, a model for the ideal packing of alkane molecules with particular reference to alcohol- and silane-coated silica surfaces was developed for describing the contact angle for alkylthioether-coating gold surfaces.
26 citations
References
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Book•
01 Jan 1983
4,689 citations
TL;DR: In this paper, a compilation of all published measurements of electron inelastic mean free path lengths in solids for energies in the range 0-10 000 eV above the Fermi level is presented.
Abstract: A compilation is presented of all published measurements of electron inelastic mean free path lengths in solids for energies in the range 0–10 000 eV above the Fermi level. For analysis, the materials are grouped under one of the headings: element, inorganic compound, organic compound and adsorbed gas, with the path lengths each time expressed in nanometers, monolayers and milligrams per square metre. The path lengths are vary high at low energies, fall to 0.1–0.8 nm for energies in the range 30–100 eV and then rise again as the energy increases further. For elements and inorganic compounds the scatter about a ‘universal curve’ is least when the path lengths are expressed in monolayers, λm. Analysis of the inter-element and inter-compound effects shows that λm is related to atom size and the most accuratae relations are λm = 538E−2+0.41(aE)1/2 for elements and λm=2170E−2+0.72(aE)1/2 for inorganic compounds, where a is the monolayer thickness (nm) and E is the electron energy above the Fermi level in eV. For organic compounds λd=49E−2+0.11E1/2 mgm−2. Published general theoretical predictions for λ, valid above 150 eV, do not show as good correlations with the experimental data as the above relations.
4,486 citations
TL;DR: In this paper, the authors used contact angles and optical ellipsometry to study the kinetics of adsorption of monolayer films and to examine the experimental conditions necessary for the formation of high-quality films.
Abstract: : Long-chain alkanethiols, HS(CH2)nX, adsorb from solution onto gold surfaces and form ordered, oriented monolayer films. The properties of the interfaces between the films and liquids are largely independent of chain length when n > 10; in particular, wetting is not directly influenced by the proximity of the underlying gold substrate. The specific interaction of gold with sulfur and other soft nucleophiles and its low reactivity toward most hard acids and bases make it possible to vary the structure of the terminal group, X, widely and thus permit the introduction of a great range of functional groups into a surface. Studies of wettability of these monolayers, and of their composition using X-ray photoelectron spectroscopy (XPS), indicate that the monolayers are oriented with the tail group, X, exposed at the monolayer-air or monolayer- liquid interface. The adsorption of simple n-alkanethiols generates hydrophobic surfaces whose free energy (19 mJ/sq. m) is the lowest of any hydrocarbon surface studied to date. Measurement of contact angles is a useful tool for studying the structure and chemistry of the outermost few angstroms of a surface. This work used contact angles and optical ellipsometry to study the kinetics of adsorption of monolayer films and to examine the experimental conditions necessary for the formation of high-quality films.
3,193 citations
TL;DR: In particular, the ratio of the concentration of the t\r'o components in a mixed monolayer is not the same as in solution but reflects the relative solubilities of the components in solution and interactions between the tail groups, X, in the monolayers as discussed by the authors.
Abstract: Long-chain alkanethiols, HS(CH2)nX, adsorb from solution onto gold and form oriented. ordered monolayers. Monolayers exposing more than one functional group at the surface can be generated by coadsorption of t*'o or more thiols from solution. In general, the ratio of the concentration of the t\r'o components in a mixed monolayer is not the same as in solution but reflects the relative solubilities of the components in solution and interactions between the tail groups, X, in the monolayers. Multicomponent monolayers do not phase-segregate into single-component domains large enough to influence the contact angle (a few tens of angstroms across) and also do not act as ideal two.dimensional solutions. In the two-component system HS(CH2)J/HS(CH2)"CH3 in ethanol, where X is a polar tail group such as CH2OH or CN, adsorption of the polar component is particularly disfavored at low concentrations of the polar component in the monolayer. These isotherms may arise from poor solvation of the polar tail groups in the quasi-two-dimensional alkane solution provided by the methyl tail groups. From dilute solutions in alkanes, adsorption of HS(CH2)r9CH2OH is strongly preferred over HS(CHz)roCHr, probably due to the stabilization afforded by intramonolayer hydrogen bonds between the hydroxyl tail groups. The wettability of mixed monolayers is not linear in the composition of the surface. (n a surface comprised of a polar and a nonpolar component, the polar component is more hydrophilic when its concentration in the monolayer is low than when the monolayer is composed largely of the polar component.
900 citations
TL;DR: In this paper, a phenomenes de mouillage et d'adsorption d'une surface solide are described, e.g., adaption of alcanethiols and sulfures de dialkyl sur de l'or
Abstract: Etude des phenomenes de mouillage et d'adsorption d'une surface solide. Application a l'adsorption d'alcanethiols et de sulfures de dialkyl sur de l'or
868 citations