Photoelectron mean free paths in barium stearate layers

Hall, S.M.; Andrade, Joseph D.; Ma, Shuangyun; King, Robert N.

doi:10.1016/0368-2048(79)85039-2

Cited by 32 publications

(3 citation statements)

References 5 publications

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“…The pronounced takeoff angle dependence of the data in Table (the atomic concentration of nitrogen and silicon detected at 75° is about half of that detected at 15°, thus, is due entirely to that detected at 15°), indicates that the amidopropylsilane functionality is confined to the outer ∼10 Å of the film samples. Values for λ in organic materials are somewhat controversial, ranging from the low values reported by Clark 38 to higher values reported by others, and we know nothing about the mean free paths of photoelectrons in this material. Because of this uncertainty, the 10-Å value must be considered an estimate, but we emphasize that this layer is extremely thin and very different than the cross-linked multilayer APTES network reported by Thompson et al Consistent with this picture are the C(1s) spectra that are displayed in Figure .…”

Section: Resultsmentioning

confidence: 87%

Surface Modification of Poly(ethylene terephthalate) To Prepare Surfaces with Silica-Like Reactivity

and

McCarthy

1998

Langmuir

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Reactions of semicrystalline poly(ethylene terephthalate) (PET) film with 3-aminopropyltrialkoxysilanes at the film−solution interface and subsequent hydrolysis render silanol (Si−OH) functionality that is attached to the PET surface by amide linkages (PET−CONH(CH2)3Si(OH)3). Toluene was found to be the preferred solvent for the initial amidation reaction, rendering a higher surface concentration of silanol groups than that for other solvents. Polycondensation of tetraethyl orthosilicate on the surface of PET−CONH(CH2)3Si(OH)3 produces thin silica films, the thickness of which can be controlled with reaction time. The surface of this composite film (PET−(SiO2) X −OH) also contains reactive silanol groups. These two reactive surfaces were further modified using other reactive silanes to introduce alkyl, perfluoroalkyl, bromoalkyl, and aminoalkyl functionality to the PET film surface. The surface density of attached groups was assessed by X-ray photoelectron spectroscopy, and wettability of the surfaces was determined using contact angle analysis. The reactivity of these surfaces was compared to that of oxidized silicon wafers, and we conclude that these PET modification procedures (amidation with 3-aminopropyltrialkoxysilanes and polycondensation of tetraethyl orthosilicate) produce surfaces that react with the versatility of oxidized silicon wafers.

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Section: Resultsmentioning

confidence: 87%

Surface Modification of Poly(ethylene terephthalate) To Prepare Surfaces with Silica-Like Reactivity

and

McCarthy

1998

Langmuir

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“…We can estimate the thickness of the layers and multilayers using estimates of the electron mean free path. Values for λ in organic polymers are somewhat controversial, ranging from the low values reported by Clark , to higher values reported by others. , Ashley and co-workers have developed a theoretical approach to the problem − and calculate mean free paths based on bulk density and molecular structure. The mean free paths of electrons in layer-by-layer assemblies have not been discussed in the literature and as discussed above are certainly a function of the supermolecular structure of the multilayers.…”

Section: Resultsmentioning

confidence: 99%

Layer-by-Layer Deposition: A Tool for Polymer Surface Modification

1997

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Layer-by-layer deposition of polyelectrolytes onto poly(ethylene terephthalate) (PET) film is reported as a method for polymer surface modification. Poly(allylamine hydrochloride) (PAH) and poly(sodium styrenesulfonate) (PSS) were sequentially adsorbed to unmodified (neutral) PET as well as PET samples that had been surface modified to contain carboxylate (PET-CO2 -) and ammonium (PET-NH3 + ) functionality. XPS and contact angle data indicate that the layers are extremely thin (2-6 Å) and stratified to a significant extent. The wettability of the multilayer films is controlled by the outermost polyelectrolyte layer and the thickness of the individual layers (sublayers have an influence in multilayers with thinner layers). The substrate surface chemistry controls the thickness of all of the layers in the multilayer assembly as well as the stoichiometry (ammonium ion:sulfonate ion ratio) of the deposition process. The effect of the ionic strength of the polyelectrolyte solutions was studied for the case of the neutral substrate (PET); both the individual layer thickness and deposition stoichiometry are affected by ionic strength. Peel tests indicate that the multilayer assemblies have significant mechanical strength.

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“…Yet even within measurements on a particular type of material large variations in results occur. For example, attenuation lengths of between ∼10 and ∼100 Å have been reported for organic material at a kinetic energy of 1200 eV. − The discrepancies in these data are most likely due to difficulties in preparing even films of controlled thickness using techniques such as evaporation of C-containing molecules or Langmuir−Blodgett film deposition.…”

Section: Introductionmentioning

confidence: 99%

Attenuation Length of Electrons in Self-Assembled Monolayers of n-Alkanethiols on Gold

1999

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The interaction of both photoelectrons and X-rays with self-assembled monolayers of n-alkanethiols on gold has been measured using synchrotron radiation as the photon source in the energy range 140−1100 eV. The attenuation length of photoelectrons (λ) was found to vary from a minimum of ∼5 Å at an electron kinetic energy (E) of 100 eV up to ∼23 Å at a kinetic energy of 1000 eV and can be described by the expression λ = 0.3E 0.64 in the range 300−1000 eV. Exposure of the self-assembled monolayer to X-rays leads to fission of the C−S bond with a cross section of the order of 10-17 cm2 which diplays no apparent dependence on the incident photon energy.

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Photoelectron mean free paths in barium stearate layers

Cited by 32 publications

References 5 publications

Surface Modification of Poly(ethylene terephthalate) To Prepare Surfaces with Silica-Like Reactivity

Surface Modification of Poly(ethylene terephthalate) To Prepare Surfaces with Silica-Like Reactivity

Layer-by-Layer Deposition: A Tool for Polymer Surface Modification

Attenuation Length of Electrons in Self-Assembled Monolayers of n-Alkanethiols on Gold

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