Optical second harmonic generation from a catalytically active molybdenum electrode

Second harmonic generation (SHG) from an electrochemically controlled Mo surface is detected by using 7 ns laser pulses at a fundamental wavelength of 1064 nm. When this electrode is used as a catalytic support for hydrogen evolution, the optical signal shows a correlation with the reaction current. Considerations of surface kinetics indicate that this observed correlation is a result of free electron-mediated changes in surface conditions. The results of this work reinforce the currently recognized utility of SHG as a probe of reactive metal surfaces. These new data for Mo also contribute to the expansion of the presently known domain of SHG studies of electrochemical systems.