The Au(110) surface in electrochemical environment (0.1 M Na2SO4 solution) has been studied by in situ reflectance anisotropy spectroscopy (RAS) and by in situ scanning tunneling microscopy (STM). Three ranges of applied potential could be determined: negative potential (≈︂ —0.6 V vs. Ag/AgCl) where a clear (1 × 3) reconstruction is obtained; positive potential (≈︂0.6 V) where the surface is unreconstructed; and intermediate potential where the surface displays both mixed (1 × 3) and (1 × 2) domains. The significant differences in the RAS curves for the differently reconstructed Au(110) surfaces are attributed both to the local‐field effect acting on the interband transitions at the surface, and to the changes of free electron relaxation time in the [001] direction (perpendicular to the atomic rows) due to different corrugations of the surface.

Flatband potential false(VFBfalse) of (100)‐oriented normaln‐normalGaAs electrodes in various aqueous solutions have been determined by ac impedance measurements. The Nernstian variation of VFB with pH (−60 mV/pH) was verified in both indifferent electrolytes and redox‐couple solutions. Taking into account this pH dependence, the barrier height φB of the normaln‐normalGaAs/normalliquid junction with various redox couples could be calculated. φB was determined at the point of zero zeta potential (PZZP), where the voltage drop due to specific adsorption of OH groups vanishes. A pH (PZZP) of 2.8 was estimated from published data for the electron affinity of normalGaAs . The variation of φB as a function of redox potential at the normalGaAs/normalliquid junction could then be quantified through the slope S of the φB false(Vnormalredoxfalse) straight line. A value of S≃0.8 was found, showing that Fermi level pinning is much weaker than at the normalGaAs/normalmetal junction, at which one has S≃0.05 . The behavior is confirmed by published data on normalp‐normalGaAs and polymer‐coated normaln‐normalGaAs . We discuss these results within the framework of recent works on the semiconductor/metal Schottky barrier.