Page 53 - MODERN ASPECTS OF ELECTROCHEMISTRY

Zbigniew KoczorowskiA
°
For N →0, the second term in Eiq. (29) approaches 0, and we can
B
s
obtain the slope of the relationship ∆χ = f (N B ):
= const = const p – (30)
N →0
B
The expression in brackets is a more usable dependency [Eq. (30)] and
describes the physical sense of the apparent dipole moment p. The model
up to now has been used only for adsorption from solution.
The models presented above have also been reviewed in Ref. 18.
Recently, an expression for the adsorption potential at the free water
surface based on a combination of the electrostatic theory of dielectrics
and classical thermodynamics has also been proposed. 115
The popular applications of the adsorption potential measurements
are those dealing with the surface potential changes at the water/air and
water/hydrocarbon interface when a monolayer film is formed by an
adsorbed substance. 4–8,10–14,18,108,109 Phospholipid monolayers, for in-
stance, formed at such interfaces have been extensively used to study the
surface properties of the monolayers. These are expected to represent, to
some extent, the surface properties of bilayers and biological as well as
various artificial membranes. An interest in a number of applications of
ordered thin organic films (e.g., Langmuir and Blodgett layers) dominated
research on the insoluble monolayer during the past decade.
Research on the adsorption potentials of aqueous solutions containing
various short-chain organic compounds, developed mainly by
Kamien ′ ski's school, 49,116 is still intensively continued by his succes-
sors. 103–110 The investigations also deal with mixed adsorbate sys-
tems. 117,118
Our laboratory has investigated adsorption behavior at air/water and
Hg/water interfaces, the adsorption potentials caused by the aliphatic
119 120 121 122
nitriles, dinitriles, monoalkyl ethers, dialkylethers, propalgyl
alcohol, 123,124 and dimethysulfoxide. 125 The influence of the relative
positions of two OH groups using the isomeric butanodiols has been also
studied. 126
Adsorption potential shifts are higher at the air/solution than at the
Hg/solution interface. This aspect has been discussed in terms of nonlocal
electronic effects in the metal surface and different molecular orientation
atthetwointerfacee. 119–120