Surface properties of electrolyte solutions studied with ion beam analysis

The charge distribution near the surface of solutions with ionic surfactants is investigated with neutral impact collision ion scattering spectroscopy (NICISS). The concentration depth profiles of both, cations and anions, can routinely be determined by NICISS. In principle this would allow to determine the surface potential. It is not, however, a routine task to gauge the depth scale of both ions relative to each other. This is caused by the fact that the projectiles lose energy not only elastically but also inelastically during back scattering. The last has to be determined experimentally. We determine the inelastic loss of energy from spectra of the gas phase of volatile substances which consist of the desired elements. The influence of the FWHM of the peaks found in the gas phase spectra on the deconvolution of the spectra of the different species is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.