The simple electrochemical method for detection of 3d molecular reorientation in adsorbed layers of organic substances

Gašparović, Blaženka; Risović, Dubravko; Ćosović, Božena

doi:10.1016/j.jelechem.2004.07.035

Cited by 6 publications

(2 citation statements)

References 11 publications

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“…33 In twodimensional condensed systems the occurrence of a minimum, if not of the discontinuity, in κ s positioned exactly at the critical concentration has been interpreted as a thermodynamic signature of an interaction-driven phase transition 39,40 predicted and discussed in theoretical works. 46 It can provide information on monolayer growth [20][21][22] or on subtle structural changes such as those related to molecular reorientation in a surface adlayer 47,48 or even on mechanisms responsible for the formation of a considered structure. Generally, the concept of fractal dimension proved to be efficient in the description of complex morphologies through the use of a single topography descriptor-the fractal dimension of the surface.…”

Section: Theorymentioning

confidence: 99%

Application of Brewster angle microscopy and fractal analysis in investigations of compressibility of Langmuir monolayers

Risović

Frka²,

Kozarac³

2011

The Journal of Chemical Physics

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The aim of this study was to investigate the connection between the lipid/amphiphile monolayer structure at the interface and its macroscopic/rheological properties, in particular, to establish the link between the fractality of the monolayer structure and its compressibility modulus. To that purpose we have used fractal analysis of images obtained by Brewster angle microscopy to infer the fractal dimension of the monolayer structure and relate its change to the corresponding changes in compressibility derived from a simultaneously measured π-A isotherm. The results of the study confirmed the starting assumption based on theoretical considerations that the fractal dimension of an amphiphilic monolayer and its compressibility should be correlated. We have shown that there exists a strong correlation between the fractal dimension and the corresponding compressibility modulus of different amphiphilic materials. Thus, confirming the link between the short ordered structure on the molecular level and the macroscopic property-compressibility of the monolayer. The established correlation between the fractal dynamics and compressibility modulus of the monolayer enabled identification of onset of percolation-a second-order phase transition that is otherwise not easy and unambiguously detectable. We have found that the signature of percolation in a monolayer, regardless of its composition, is the occurrence of a sharp increase (a jump) of compressibility modulus (at macroscopic level) at the characteristic value of the corresponding fractal dimension D = 1.89. This is the result of the abrupt establishment of a connected structure on the molecular level, consequently involving a change in the elastic properties of the monolayer on a macroscopic scale. The results of this investigation provide means for unambiguous identification of the onset of percolation in the Langmuir layer and should facilitate a more efficient application of the percolation theory in further study of processes and structures at the interface during the monolayer compression.

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Section: Theorymentioning

confidence: 99%

Application of Brewster angle microscopy and fractal analysis in investigations of compressibility of Langmuir monolayers

Risović

Frka²,

Kozarac³

2011

The Journal of Chemical Physics

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“…The measurement of ac current as a function of electrode potential is called tensammetry [5]. It is used for the determination of adsorption parameters [2,6], the influence of SAS molecular structure on the SAS surface activity [3,7], the structure of adsorbed layer [8][9][10][11][12], the reorientation of molecules in the adsorbed layer [13][14][15] and the concentration of SAS in natural waters [16,17].…”

Section: Introductionmentioning

confidence: 99%

A theory of square-wave voltammetry of surface-active, electroinactive compounds

Jadreško

Lovrić

2008

Electrochimica Acta

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The influence of frequency on fractal dimension of adsorbed layers

Gašparović

Risović

Ćosović

et al. 2007

Electrochimica Acta

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Ac voltammetry and electrochemical impedance spectroscopy are often the methods of choice for use in study of adsorption of organic molecules. The adsorption of organic molecules on interface may results in formation of fractal structures, whose fractal dimension can be estimated using the method of scaling the hanging mercury drop electrode (HMDE). The aim of present study was to check whether the estimated fractal dimension, D (or for that matter the fractal ordering of the adsorbed layer)shows any correlation (dependence) with change of applied frequency, and second, to check the possibility to extend the method to broad frequency spectrum compatible with impedance spectroscopy. The investigation included two surfactants nonionic Triton-X-100 (T-X-100) and anionic sodium dodecyl sulfate (SDS) and alcohol tertbutanol. All measurements were performed on HMDE at thermodynamic equilibrium employing broad frequency spectrum. The validity of the approach was checked by measurements on pure electrolyte and by comparison with previously obtained results for fractal layers. The results of the investigations show that: (1) the method of scaling the HMDE to obtain the fractal dimension of adsorbed layer is compatible with impedance spectroscopy and the combination of these methods can be used as a powerful tool to investigate fractal aspect of adsorption of organic molecules; (2) fractal ordering of adsorbed layer and the value of fractal dimension is not influenced by the frequency of applied sinusoidal voltage perturbations.

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The simple electrochemical method for detection of 3d molecular reorientation in adsorbed layers of organic substances

Cited by 6 publications

References 11 publications

Application of Brewster angle microscopy and fractal analysis in investigations of compressibility of Langmuir monolayers

Application of Brewster angle microscopy and fractal analysis in investigations of compressibility of Langmuir monolayers

A theory of square-wave voltammetry of surface-active, electroinactive compounds

The influence of frequency on fractal dimension of adsorbed layers

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