Determination of the optical properties of silicon/silica surfaces by means of ellipsometry, using different ambient media

Landgren, Mikael; Joensson, Bengt

doi:10.1021/j100110a030

Cited by 199 publications

(211 citation statements)

References 2 publications

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“…The influence of the silicon oxide layer is accounted for, using the methods suggested by Landgren and Jönsson. 40 All measurements were conducted at a wavelength of 401.5nm, with an incident angle of 67.87 • . The experiments were performed in situ at a temperature of 25 • C, using a 5mL trapezoid cuvette made of optical glass and fitted with a magnetic stirrer, rotating at a speed of 300 rpm.…”

Section: Methodsmentioning

confidence: 99%

Polyelectrolyte Adsorption on Solid Surfaces: Theoretical Predictions and Experimental Measurements

Xie¹,

Nylander²,

Piculell³

et al. 2013

Langmuir

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This work utilizes a combination of theory and experiments, to explore the adsorption of two different cationic polyelectrolytes onto oppositely charged silica surfaces, at pH 9.Both polymers, Poly(diallyldimethylammonium chloride), PDADMAC, and Poly(4-vinyl Nmethylpyridinium iodide), PVNP, are highly charged, and highly soluble in water. Another important aspect is that a silica surface carries a relatively high surface charge density, at this pH level. This means that we have specifically chosen to investigate adsorption under conditions where electrostatics can be expected to dominate the interactions. Of specific focus in this work is the response of the adsorption to the addition of simple salt, i.e. a process * To whom correspondence should be addressed 1 where electrostatics is gradually screened out. Theoretical predictions from a recently developed correlation-corrected classical density functional theory for polyelectrolytes, are evaluated by direct quantitative comparisons with corresponding experimental data, as obtained by ellipsometry measurements. We find that, at low concentrations of simple salt, the adsorption increases with ionic strength, reaching a maximum at intermediate levels (about 200 mM). The adsorption then drops, but retains a finite level even at very high salt concentrations, indicating the presence of non-electrostatic contributions to the adsorption. In the theoretical treatment, the strength of this relatively modest, but otherwise largely unknown, non-electrostatic surface affinity, was estimated by matching predicted and experimental slopes of adsorption curves at high ionic strength. Given these estimates for the non-electrostatic part, experimental adsorption data are essentially captured with quantitative accuracy by the classical density functional theory.

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Section: Methodsmentioning

confidence: 99%

Polyelectrolyte Adsorption on Solid Surfaces: Theoretical Predictions and Experimental Measurements

Xie¹,

Nylander²,

Piculell³

et al. 2013

Langmuir

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show abstract

“…Next, the surface was vertically mounted into a glass trapezoid cuvette (Hellma, Germany) containing 5 ml of solution thermostated at 25°C and equipped with magnetic stirrer. Additional specification of the ellipsometer setup is described by Landgren and Jönsson [50]. In order to determine the refractive index of the gold surface, prior to each measurement, a twozone surface characterization in solution was carried out.…”

Section: Ellipsometrymentioning

confidence: 99%

Polymer multilayer film formation studied by in situ ellipsometry and electrochemistry

Haberska

Ruzgas

2009

Bioelectrochemistry

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Polyelectrolyte multilayer films adsorbed on gold surfaces were studied by combined ellipsometric and electrochemical methods. Multilayers were composed of "synthetic" (poly(4-styrenesulfonic acid) ammonium salt (PSS) and poly(allylamine hydrochloride) (PAH) (PSS/PAH)) and "semi-natural" (carboxymethyl cellulose (CMC) and chitosan (CHI) (CMC/CHI)) polyelectrolytes. It was found that only PSS/PAH Layer-by-Layer (LbL) assembled structures result in dense surface confined films that limit permeability of small molecules, such as ferri-/ferrocyanide. The PSS/PAH assemblies can be envisaged as films with pinholes, through which small molecules diffuse. During the LbL deposition process of these films a number of pinholes quickly decay. A representative pinhole diameter was found to be approximately 20 μm, which determines the diffusion of small molecules through LbL films, and yet remains constant when the film consists of a few LbL assembled polyelectrolyte bilayers. CMC/CHI LbL assemblies at gold electrode surfaces give very low density films, which do not limit the diffusion of ferri-/ferrocyanide between the surface of the electrode and the solution.

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“…The adsorption of HS-PG and of the lipoproteins was monitored by in situ ellipsometry, as detailed previously [19][20][21]. All measurements were carried out with an Optrel Multiskop (Optrel, Kleinmachnow, Germany) at 532 nm.…”

Section: Ellipsometry Measurementsmentioning

confidence: 99%

Reduction of Arteriosclerotic Nanoplaque Formation and Size by n-3 Fatty Acids in Patients after Valvular Defect Operation

Rodríguez¹,

Winkler²,

Pietzsch³

et al. 2009

Complement Med Res

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Background/Methods: Coating a silica surface with the isolated lipoprotein receptor heparan sulfate proteoglycan (HS-PG) from arterial endothelium and vascular matrices, we could observe the very earliest stages of arteriosclerotic plaque development by ellipsometric techniques in vitro (patent EP 0 946 876). This so-called nanoplaque formation is represented by the ternary aggregational complex of the HS-PG receptor, lipoprotein particles and calcium ions. The model was validated in several clinical studies on statins in cardiovascular high-risk patients applying their native blood lipoprotein fractions. Results: In 7 patients who had undergone a valvular defect operation, the reduction of arteriosclerotic nanoplaque formation in normal Krebs solution amounted to 6.1 ± 2.3% (p < 0.0156) and of nanoplaque size to 37.5 ± 13.2% (p < 0.0312), respectively, after a 3-month therapy with n-3 fatty acids (3 ··3 g daily, Ameu® 500 mg). Additionally, the quotient oxLDL/LDL was lowered by 6.8 ± 2.1% (p < 0.0166), the MDA concentration remained unchanged and the lipoprotein(a) concentration decreased by 15.8 ± 5.6% (p < 0.0469) in the patients’ blood. The concentration of the nanoplaque promoting particles VLDL and total triglycerides was diminished by 34.1 ± 11.6% (p < 0.0469) and 26.7 ± 10.8% (p < 0.0156), respectively. Furthermore, the ratio of the strongly atherogenic small dense to the total LDL cholesterol (LDL5+LDL6)/LDLtot decreased by 9.9 ± 3.0% (p < 0.0174). Conclusions: A combinatorial regression analysis revealed a basis for a mechanistic explanation of nanoplaque reduction under n-3 fatty acid treatment. This effect was possibly due to the beneficial changes in lipid concentrations and an attenuation of the risk factors oxLDL/LDL and (LDL5+LDL6)/LDLtot.

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Determination of the optical properties of silicon/silica surfaces by means of ellipsometry, using different ambient media

Cited by 199 publications

References 2 publications

Polyelectrolyte Adsorption on Solid Surfaces: Theoretical Predictions and Experimental Measurements

Polyelectrolyte Adsorption on Solid Surfaces: Theoretical Predictions and Experimental Measurements

Polymer multilayer film formation studied by in situ ellipsometry and electrochemistry

Reduction of Arteriosclerotic Nanoplaque Formation and Size by n-3 Fatty Acids in Patients after Valvular Defect Operation

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