SURFACE-CHARGE DEPENDENCE OF 2ND-HARMONIC GENERATION FROM A BRASS ELECTRODE

Optical second harmonic generation from a polycrystalline brass (63% Cu, 37% Zn) surface is detected with fundamental wavelengths of 1064 and 532 nm. The sample is electrochemically controlled in the absence of faradaic processes. Effects of the solution environment are separately studied in 0.5 M aqueous electrolytes of NaClO4 and Na2SO4. The second harmonic response of the electrode to surface charge variations is probed by combining optical experiments with differential capacitance measurements. The results are compared with those for a polycrystalline Cu electrode treated under similar conditions. From this comparison, it is demonstrated that the surface charge effects for the brass electrode closely follow the behavior of its main constituent Cu, displaying an apparently strong role of bound electron mediated surface optical response.