Ellipsometry Study of the Adsorption of Molecules at Electrolyte Interfaces with Gold and Stainless Steel

Beaglehole, D.; Webster, B.J.; Werner, Sebastian

doi:10.1006/jcis.1998.5475

Cited by 26 publications

(19 citation statements)

References 17 publications

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“…Another set of experiments was performed using various Cl À concentrations on a freshly polished and activated Au electrode which was dipped for 30 min in a 1.2 g L À1 BSA aqueous solution prior to electrochemical measurements. BSA is a high molecular weight protein known to adsorb onto surfaces and thus prevents further sorption process [31]. Fig.…”

Section: Resultsmentioning

confidence: 99%

Hg(II) trace electrochemical detection on gold electrode: Evidence for chloride adsorption as the responsible for the broad baseline

Hezard

Laffont

Gros

et al. 2013

Journal of Electroanalytical Chemistry

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Investigations were performed in order to clarify the origin of the broad baseline observed during Hg(II) trace electrochemical detection on gold electrode in the presence of Cl À anions. The influence of Cl À concentration on the shape of the voltammograms was studied in the presence and in the absence of Bovine Serum Albumin (BSA) in order to bring out adsorption/desorption processes. On the basis of these experiments, and contrary to what has been proposed by several authors in the literature, it was proved that the broad baseline does not result from calomel (Hg 2 Cl 2) formation but is rather related to an interaction between Cl À and polycrystalline Au electrode surface. The evolution of the shape of the baseline was also studied in the presence of other halide anions, namely F À , Br À , and I À. The latter two were found to induce a broad baseline similar to that recorded in the presence of Cl À. Finally, it was shown that BSA addition is not suitable for Hg(II) detection since it prevents Hg(0) deposition onto the electrode surface.

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Section: Resultsmentioning

confidence: 99%

Hg(II) trace electrochemical detection on gold electrode: Evidence for chloride adsorption as the responsible for the broad baseline

Hezard

Laffont

Gros

et al. 2013

Journal of Electroanalytical Chemistry

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“…The influence of an applied electric potential on the adsorption of charged macromolecules (mainly proteins) has been the subject of several previous investigations (19,20,(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44). Although most of these studies note an influence of substrate potential on adsorption, changes are typically within a factor of two or so, and to our knowledge no continuous adsorption has been reported.…”

Section: Discussionmentioning

confidence: 99%

Continuous polyelectrolyte adsorption under an applied electric potential

Ngankam

Tassel

2007

Proc. Natl. Acad. Sci. U.S.A.

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Interactions between charged macromolecules (e.g., proteins, nucleic acids, polyelectrolytes) and charged surfaces govern many natural and industrial processes. We investigate here the influence of an applied electric potential on the adsorption of charged polymers, and report the following significant result: the adsorption of certain amine side chain-containing polycations may become continuous, i.e., asymptotically linear (or nearly linear) in time over hours, upon the application of a modest anodic potential. Employing optical waveguide lightmode spectroscopy (OWLS) and an indium tin oxide (ITO) substrate, we show that asymptotic kinetics, and the adsorbed mass at the onset of the asymptotic regime, depend sensitively on polymer chemistry (in particular, side chain volume and charge location), increase with applied potential and ionic strength (conditions favoring a thicker initial layer), and are independent of bulk polymer concentration (suggesting postadsorption events to be rate limiting). X-ray photoelectron spectra reveal a suppressed polymer charge within layers formed via continuous adsorption, but no evidence of electrochemical reactions. We propose a mechanism based on polymer-polymer binding within the adsorbed layer, enabled by suppressed electrostatic repulsion and/or enhanced ionic correlations near the conducting surface, and stabilized by short-range attractive interactions. Continuous adsorption under an applied electric potential offers the possibility of nanoscale films of tailored polymer content realized in a single step.optical waveguide lightmode spectroscopy ͉ poly(L-lysine) ͉ protein adsorption ͉ indium tin oxide I nteractions between charged macromolecules and charged surfaces are ubiquitous in nature (e.g., protein-cell membrane) and are often exploited in technological applications. For example, weakly charged colloidal systems such as paints, inks, and waste water may be stabilized through an adsorbed layer of charged polymer (polyelectrolyte) (1, 2), and polyelectrolyte films containing functional entities (e.g., biomolecules, nanoparticles) may serve as sensors, separation membranes, and electrochemical components (3, 4). Adsorption is usually spontaneous, with electrostatic interactions naturally playing a key role. These interactions, and therefore the adsorption process itself, may be controlled through solution variables such as salt concentration and pH (5-12). However, there generally exists an upper limit to the extent of polyelectrolyte adsorption. The typical situation is for adsorption to be quite rapid (usually at a transport limited rate) and then to saturate, corresponding to the point where interfacial charge accumulation suppresses additional (net) adsorption (1). A clever way to avoid this limit is through the layer-by-layer (LbL) method, where a substrate is alternately exposed to solutions of oppositely charged polyelectrolytes (3, 13). Each exposure results in an increase in adsorbed mass and an overall interfacial charge reversal. The LbL method allows one t...

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“…21,22 Results Fig. Changes to the surface upon exposure to the electrolyte under potential and the presence of any adsorbed species were modeled by changes in t m .…”

Section: Methodsmentioning

confidence: 99%

Competitive Adsorption of PEG, Cl[sup −], and SPS/MPS on Cu: An In Situ Ellipsometric Study

Walker

Richter

Moffat

2006

J. Electrochem. Soc.

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The adsorption of Cu electrodeposition accelerating agents bis-͑3-sodiumsulfopropyl disulfide͒ ͑SPS͒ and ͑3-mercaptopropyl͒ sulfonate ͑MPS͒ on evaporated Cu thin films was examined in situ using spectroscopic ellipsometry under quiescent conditions. Both the thiol MPS and disulfide SPS resulted in definitive changes in the optical response of the interface, indicative of irreversible chemisorption. The optical responses of the films formed from the two additives were different, however, suggesting a difference in the adsorbed states. Cl − can reversibly coadsorb with either MPS or SPS. Preadsorption of either MPS or SPS inhibits the specific adsorption of polyethylene glycol ͑PEG͒ in the presence of Cl − . Both SPS and MPS adsorption displace preadsorbed PEG layers. The kinetics of the PEG displacement reaction differ significantly between the thiol and disulfide, consistent with observations of their respective effect on metal deposition kinetics.

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Ellipsometry Study of the Adsorption of Molecules at Electrolyte Interfaces with Gold and Stainless Steel

Cited by 26 publications

References 17 publications

Hg(II) trace electrochemical detection on gold electrode: Evidence for chloride adsorption as the responsible for the broad baseline

Hg(II) trace electrochemical detection on gold electrode: Evidence for chloride adsorption as the responsible for the broad baseline

Continuous polyelectrolyte adsorption under an applied electric potential

Competitive Adsorption of PEG, Cl[sup −], and SPS/MPS on Cu: An In Situ Ellipsometric Study

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