Bv. Zhmud et al., EVALUATION OF SURFACE-IONIZATION PARAMETERS FROM AFM DATA, Journal of colloid and interface science (Print), 207(2), 1998, pp. 332-343
A new application of atomic force microscopy (AFM) for evaluation of s
urface ionization parameters on the basis of a charge-regulation model
is demonstrated. Interactions between symmetrical silicon nitride and
silica surfaces have been measured in aqueous electrolytic solutions
at different pHs and separations from a few Debye lengths down to zero
. The obtained experimental data are reported and interpreted on a qua
ntitative level in the framework of Dejaguin's approximation; the comp
utational procedure used for this purpose is outlined. Surface charge
density, surface potential, and species concentrations are calculated
as functions of pH and separation, unveiling the limits of applicabili
ty of classical constant-charge and constant-potential approximations.
The integrity of the results on the charge properties of interacting
surfaces is discussed in reference to electrokinetic and titration dat
a, potential problems caused by the existence of non-DLVO forces and s
urface irregularities being highlighted. (C) 1998 Academic Press.