Gas‐phase electrochemistry. I. Electrocapillary effects at the mercury‐gas interface

The first phase of a systematic study of the electrochemical phenomena at the metal‐gas interface is presented. An experimental and theoretical analysis of the phenomenon of electrocapillarity at the metal‐gas interface is described. Experimental curves of the relative reduction of surface tension vs applied potential were obtained at the interface between a mercury electrode and vacuum or He, HBr, and ethanol at various bulk pressures. The electrocapillary curves resemble the theoretical electrocapillary curves obtained from first principles. The potential of the maximum surface tension is at zero voltage. At 4 kV the surface tension decreases significantly. The variation in the surface tension at this voltage is about 100 erg cm−2. The electrocapillary curve at the mercury‐He interface approaches the ’’vacuum’’ curve. The effect of ethanol involves an absolute depression of the surface tension, but the general shape remains the same as that of He. The HBr curve differs from all others due to surface rea...