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An indirect laser-induced temperature jump determination of the surface pKa of 11-mercaptoundecanoic acid monolayers self-assembled on gold

Article Abstract:

The acidity (pKa) of monolayers made up of 11-mercaptoundecanoic acid self-assembled on vapor-deposited gold film electrodes in contact with either 0.10 or 1.0 M ionic strength NaClO4 electrolyte solutions have been measured through indirect laser-induced temperature jump method. The pKa is defined as the value of the pH of the solution in contact with the monolayer when half of the acid functional groups have been ionized. Results indicated that pKa has a value of 5.7 +/- 0.2 at O.10 M ionic strength and 4.4 +/- 0.2 at 1.0 M ionic strength.

Measurement, Thin films, Monomolecular films, Acidity function

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Principle of unchanging total concentration and its implication for modeling unsupported transient voltammetry

Article Abstract:

The electrochemistry of solutions with little or no added supporting electrolyte has been studied. Attention was given to the oxidation or reduction of an anion or a cation to produce another ion of the same sign as the reactant. Theoretical calculations and analyses were simplified by using the principle that the total solute concentration remains the same when the diffusivities of the solute species do not deviate significantly from a common value.

Models, Electrochemistry, Electrochemical analysis, Voltammetry

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Dimensional analysis of chronoamperometry: proof and verification of Cottrellian behavior of systems with composition-dependent diffusion coefficients

Article Abstract:

The simulations of various examples of semi-infinite linear diffusional and migrational systems with compositionally dependent diffusion coefficients are done. It is inferred that chronoamperometry of an initially homogeneous system with Dirichlet boundary conditions and semi-infinite linear diffusion will always show Cottrellian behavior and that the product [it.sub.1/2] is constant as a function of time till the system is initially homogeneous.

Analysis, Usage, Diffusion, Diffusion (Physics), Boundary value problems, Conductometric analysis

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