What do linear and nonlinear optical techniques have to offer for the investigation of adsorption layers of soluble surfactants?

Motschmann, H.; Teppner, Renate; Bae, Sung Jin; Haage, K.; Wantke, D.

doi:10.1007/s003960050535

Cited by 11 publications

(9 citation statements)

References 3 publications

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“…However, the above mentioned methods have been used to compare the experimentally determined surface excess and the surface excess calculated via the Gibbs equation in several cases. Due to the reasons mentioned above the activity coefficient has been unknown in all these cases and is either assumed to be constant or calculated from the Debye‐Hückel limiting law despite the fact that the Debye‐Hückel theory has been developed only for point charges and not for large ions like ionic surfactants. In several cases discrepancies between the experimentally determined surface excess and that calculated via the Gibbs equation are found .…”

Section: Surface Spectroscopy Vs Thermodynamic Conceptsmentioning

confidence: 99%

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Thermodynamics and structure of liquid surfaces investigated directly with surface analytical tools**

Andersson

Morgner²

2017

Annalen der Physik

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Measuring directly the composition, the distribution of constituents as function of the depth and the orientation of molecules at liquid surfaces is essential for determining physicochemical properties of liquid surfaces. While the experimental tools that have been developed for analyzing solid surfaces can in principal be applied to liquid surfaces, it turned out that they had to be adjusted to the particular challenges imposed by liquid samples, e.g. by the unavoidable vapor pressure and by the mobility of the constituting atoms/molecules. In the present work it is shown, how electron spectroscopy and ion scattering spectroscopy have been used for analyzing liquid surfaces. The emphasis of this review is on using the structural information gained for determining the physicochemical properties of liquid surfaces.

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Section: Surface Spectroscopy Vs Thermodynamic Conceptsmentioning

confidence: 99%

“…and Bae et al. investigated with Second Harmonic Generation (SHG) the surface of 1‐alcyl‐4‐dimethylaminopyridinium bromide solutions in water . The SHG signal of the C12 compound was calibrated with that of the C20 and C22 surfactant, which, in contrast to the C12 compound, are insoluble in water.…”

Section: Surface Spectroscopy Vs Thermodynamic Conceptsmentioning

confidence: 99%

Thermodynamics and structure of liquid surfaces investigated directly with surface analytical tools**

Andersson

Morgner²

2017

Annalen der Physik

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“…Usually, the surface excess of a surfactant in its dilute solution is determined indirectly by surface tension measurements with the help of the Gibbs equation with the approximation that its chemical activity is equal to its bulk concentration. Neutron reflection 10,11,20 and non-linear optical methods [21][22][23][24] can measure the surface excess, however, the small inorganic counter-ions are not suitable to be measured. In our lab, the concentration-depth profiles of chemical species can be obtained from NICIS spectra.…”

Section: Results and Discussion A Surface Excessmentioning

confidence: 99%

The competitive adsorption of counter-ions at the surface of anionic surfactants solution

Wang

Morgner

2011

Phys. Chem. Chem. Phys.

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We have determined the surface excess of surface active anion and counter-ions in a non-aqueous polar solution of anionic surfactants blends, as well as their distributions near the solution surface. The blends of two anionic surfactants, sodium dodecyl sulfate (SDS) and cesium dodecyl sulfate (CDS), with different contents were used as solutes to prepare the solutions. According to the isotherms that are separately fitted to the pure SDS and the pure CDS solutions (C. Wang and H. Morgner, Langmuir, 2010, 26, 3121), CDS has a slightly but significantly higher surface excess than SDS (CDS is 14.8% higher) at the concentration of 0.04 molal kg(-1) solvent. Therefore, in this work we chose 0.04 molal kg(-1) solvent as total anion concentration and varied the contents of surfactants. From present experimental results, we found that the surface excess of anion increases slightly with the CDS in the bulk content. Importantly, the fractions of Cs(+) in cationic surface excess are higher than its contents in the bulk for all three solutions. This demonstrates that Cs(+) is more competitive than Na(+) in the adsorption. The surface structure of the solutions have been characterized by concentration-depth profiles, of Cs(+), Na(+) and of sulfur which is used to identify dodecyl sulfate. Those profiles evidence that Cs ions penetrate deeper than sodium ions into the layer formed by the heads of the anions, reducing the electrical potential of the surface more efficiently. This can be used to explain the adsorption competition between those two counter-ions. The cause that makes Cs(+) more competitive than Na(+) in the adsorption can be attributed to its less tightly bound solvation shell, and thus, to its effectively smaller ion size.

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“…31 In this context, nonlinear optical methods have been established as an alternative to study LL interfaces with much finer depth resolution. [32][33][34] In particular, in the case of surface second harmonic generation (SHG), a technique whereby two photons at a fundamental frequency o are converted into one photon at the harmonic frequency 2o, this resolution may be reduced to a single surface molecular monolayer. Such surface specificity is obtained owing to the lack of centrosymmetry of the interface compared with the two adjacent bulk solutions, the SHG signal vanishing in media with centrosymmetry within the electric dipole approximation.…”

Section: Introductionmentioning

confidence: 99%

Second harmonic generation monitoring of nitric acid extraction by a monoamide at the water–dodecane interface

Martin-Gassin

Gassin

Couston

et al. 2011

Phys. Chem. Chem. Phys.

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The interface dynamic properties of a monoamide extractant with potential for application to the front end of the nuclear cycle and to waste treatment are examined by second harmonic generation. The results are compared with bulk nitric ion titration and surface pressure measurements. SH static studies show the extractant reaching the interface and accurately match the IFT measurements. The main feature of the SH dynamic studies is a chaotic fluctuation period, strongly related to intense extraction. Fluctuations are a signature of the interface behaviour during the extraction process. Vertical development of the interface, often called protrusion, remains the most probable origin of the measured fluctuation. Additionally, interfacial measurements show a non-monotonic lag time during extraction, probably related to cooperative effects not observed in the bulk at the working concentration. Such mutual behaviour could be a supplementary prerequisite for the ion transfer across this liquid-liquid interface.

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What do linear and nonlinear optical techniques have to offer for the investigation of adsorption layers of soluble surfactants?

Cited by 11 publications

References 3 publications

Thermodynamics and structure of liquid surfaces investigated directly with surface analytical tools**

Thermodynamics and structure of liquid surfaces investigated directly with surface analytical tools**

The competitive adsorption of counter-ions at the surface of anionic surfactants solution

Second harmonic generation monitoring of nitric acid extraction by a monoamide at the water–dodecane interface

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