mesoporous thin films studied by Atmospheric Ellipsometric Porosimetry: A case of contamination

Dubreuil, Olivier; Dewalque, Jennifer; Chêne, Grégoire; Mathis, François; Spronck, Gilles; Strivay, David; Cloots, Rudi; Henrist, Catherine

doi:10.1016/j.micromeso.2011.04.013

Cited by 8 publications

(5 citation statements)

References 45 publications

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“…Analysis of the measured RBS spectra gives pore diameters of about 11 nm. This is in reasonable agreement with results obtained by atmospheric poroellipsometry, transmission electron microscopy and internal surface area [11,12], which gave pore diameters in the range 7-12 nm. RBS of thin porous layers therefore offers the possibility to derive information about the diameter of pores in these layers.…”

Section: Discussionsupporting

confidence: 92%

“…The porosity of the deposited TiO 2 films was examined in [11,12] by transmission electron microscopy (TEM) and by atmospheric poroellipsometry (AEP). The pores were arranged in two different types of structures, depending on de-position conditions [11]: Samples deposited under 25% relative humidity (RH) and directly stabilized at 300…”

Section: Resultsmentioning

confidence: 99%

“…The pore size distributions could be fitted with two Gaussian functions having mean pore diameters of 6.6 and 7.6 nm. The widths of both Gaussian distributions were about 2 nm FWHM [12]. However, due to the somewhat unrealistic model of cylindrical pores these numbers should be treated with some care.…”

Section: Resultsmentioning

confidence: 99%

“…Ellipsometry measurements were performed on a UV-visible (from 250 nm to 1000 nm) GES5E Spectroscopic Ellipsometer from SOPRALAB, the data analysis was performed with the WINSE software. The ellipsometer was coupled with an ellipsometric porosimetry device for atmospheric poroellipsometric measurements [12]. This device consists of a chamber containing the film to analyze.…”

Section: Methodsmentioning

confidence: 99%

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Rutherford backscattering analysis of porous thin TiO2 films

Mayer

Toussaint

Dewalque

et al. 2012

Nuclear Instruments and Methods in Physics Research Section B:

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The additional energy spread due to sample porosity was implemented in the SIM-NRA simulation code, version 6.60 and higher. Deviations of the path length and energy loss distributions from the ones expected from a Poisson distribution of the number of traversed pores are taken into account. These deviations are due to the interaction of pores at higher pore concentrations by overlap or blocking. The skewnesses of the energy distributions are approximated by two-piece normal distributions with identical first three moments. Propagation of porosity-induced energy spread in thick layers is taken into account. Calculated results are compared to experimental data obtained with thin TiO 2 mesoporous films measured by Rutherford backscattering (RBS),transmission electron microscopy (TEM), and atmospheric poroellipsometry.

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Section: Discussionsupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Rutherford backscattering analysis of porous thin TiO2 films

Mayer

Toussaint

Dewalque

et al. 2012

Nuclear Instruments and Methods in Physics Research Section B:

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“…Similar to other porosimetry techniques, the isotherms obtained in the previous section were analyzed by the Kelvin equation to derive the PSD. ,,, The Kelvin equation describes the behavior of a fluid in confined spaces such as a capillary. The Kelvin radius r K equals the radius of curvature of the meniscus formed in this capillary, which depends on the relative vapor pressure p / p 0 , surface tension γ, molar volume of the adsorbate V m , contact angle θ, a geometric factor G , temperature T , and gas constant R …”

Section: Resultsmentioning

confidence: 99%

Pore Size-Dependent Structure of Confined Water in Mesoporous Silica Films from Water Adsorption/Desorption Using ATR–FTIR Spectroscopy

et al. 2019

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The local structure of water on chemically and structurally different surfaces is subject of ongoing research. In particular, confined spaces as found in mesoporous silica have a pronounced effect on the interplay between adsorbate-adsorbate and adsorbate-surface interactions. Mid-infrared spectroscopy is ideally suited to quantitatively and qualitatively study such systems as the probed molecular vibrations are highly sensitive to intermolecular interactions. Here, the quantity and structure of water adsorbed from the gas phase into silica mesopores at different water vapor pressures was monitored using mid-infrared attenuated total reflection (ATR) spectroscopy. Germanium ATR crystals were coated with different mesoporous silica films prepared by evaporation induced self-assembly. Quantitative analysis of the water bending vibration at 1640 cm-1 at varying vapor pressure allowed for retrieving porosity and pore size distribution of the mesoporous films. The results were in excellent agreement with those obtained from ellipsometric porosimetry. In addition, different degrees of hydrogen bonding of water as reflected in the band position and shape of the stretching vibrations (3000-3750 cm-1) were analyzed and attributed to high-density, unordered bulk and low-density, surface-induced ordered water. Thereby, the progression of surface-induced ordered water and bulk water as a function of water vapor pressure was studied for different pore sizes. Small pores with 5 nm diameter showed a number of two ordered monolayers, while for pores > 12 nm the number of ordered monolayers is significantly larger and agrees with the number observed on planar SiO2 surfaces.

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