In situ visible-infrared sum and difference frequency generation at the electrochemical interface

An SFG investigation of Au(111) and Au(210) electrodes in aqueous solutions containing KCN and cetylpyridinium chloride

“…Moreover a comparison of DFG and SFG spectra on a Au(1 0 0) electrode in contact with an aqueous electrolyte consisting of 0.1 M NaClO 4 and 0.05 M KCN at a single potential (E = À800 mV vs. Ag|AgCl) has been reported in [12]. The results of [11] show one potential-dependent resonance, indicating the presence of one band localised within the CN À stretching spectral range.…”

Potential-dependent structure of the interfacial water on the gold electrode

“…The doubly tunable laser system [21,22] Since the strong nonresonant contribution from the gold due to the gold d-s inter-band transition centered at 550 nm is the reason for a relatively low signal/noise ratio in the SFG spectra measured at 532 nm excitation, the suppression of the nonresonant contribution and the emphasis of the resonant contribution can be expected when the visible wavelength is tuned outside the inter-band transition [25]. The optimum wavelength for the SFG measurements of the gold surface was determined by examining the SFG spectra of the ODT monolayer adsorbed on a 30-nm thick gold film using the internal reflection geometry with various visible wavelengths in the region between 470 and 700 nm.…”

Sum-frequency generation as a vibrational and electronic probe of the electrochemical interface and thin films

“…The dip or peak shape in the SFG intensity is thus related to the phase shift between the metal and molecular contributions, which both depend on the absolute phase of the metal response / nr and on the sign of the molecular oscillator strength A CN . As a consequence, the dip shape proves that the CN orientation is the same as in the case of cyanide ions adsorbed on a gold electrode [2,19], i.e., with the nitrogen N atom pointing out the interface. In addition, it also means that the SFG response from the metal is stronger than the contribution of the cyanoacetylene [2].…”

“…Since the success of SFG spectroscopy as a vibrational probe for such systems [1], numerous works have been performed, among which we may mention the characterization of the CN/metal interface in aqueous solutions [2], the hydrogen deposition on Pt [3], the catalytic reduction process of ethanol and methanol at the Pt surface electrode with CO poisoning [4,5] in relation to the development of alcohol-based fuel cells, the effect of organic additives on electroplating on gold [6] and alloys [7].…”