Solvent structure and molecular orientation in the Hg-water
interphase is an important and previously little investigated aspect
of the electrical double-layer at charged metal interfaces. By using
pyrazine and pyridine in critical comparative experiments on
a) changes of surface dipole potential difference (Esin and Markov
effects), b) surface pressure changes and c) charge dependence
of free energy of adsorption, it is shown how the surface dipole
contribution from oriented solvent molecules may be evaluated
together with the charge-dependent distribution function for water
orientation. In the case of pyridine, orientation of the adsorbate
molecule itself occurs in a manner dependent on surface charge
on the metal and interaction with oriented and bulk solvent
molecules
