DIPOLE EFFECT OF (100) MONATOMIC STEPS OF GOLD N(111) X (100) VICINALFACES IN CONTACT WITH AQUEOUS-SOLUTIONS AND UNDER ULTRAHIGH-VACUUM

Contact potentials DELTAPHI(Au(hkl))/(111)/e of Au(11,9,9), Au(433) an d Au(755) vicinal faces situated on the [011BAR] zone were measured. T he reference is the Au(111) orientation. Measurements were carried out with a Kelvin-Zisman vibrating condensator. The linear variation of D ELTAPHI(Au(hkl))/(111)/e versus the atomic (100) step density n of eac h (hkl) face suggests that the dipole moment mu(100) induced by the st eps is identical for all vicinal faces between the (111) and the (755) face. In previous work, it was found that the variation of DELTAPHI(A u(hkl))/(111)/e versus the potential of zero charge (pzc) DELTAE(sigma = 0)Au(hkl)/(111) is also linear. It is deduced that the surface pote ntial drop [delta(chis)Au(hkl)+g(Au(hkl)(S)(dip)] due to the contact b etween the solution and the (hkl) orientation at the pzc increases whe n the surface atomic density decreases.