No signature of contact ion pairs in the K 2p Auger spectra of highly concentrated potassium halide solutions

Possible ion pair formation in highly concentrated aqueous potassium halide solutions (fluoride, chloride, and bromide) has been investigated using Auger electron spectroscopy. The potassium Auger spectra exhibit features at high kinetic energy which are related to final states with vacancies on the potassium ion and a neighbouring water molecule. The potassium ion could possibly associate with a halide ion as well, giving rise to additional final states with a vacancy on the halide instead of a water molecule which should give rise to separable spectral features. The necessity of close proximity of the ions for such decays to occur would be strong evidence that contact ions pairs are present in the solution, but no features related to final states involving the anion were observed.