Time development of sers from pyridine, pyrimidine, pyrazine, and cyanide adsorbed on ag electrodes during an oxidation-reduction cycle

Adatom Hypothesis as a Predominant Mechanism of Surface Enhanced Raman Scattering: A Review of Experimental Argumentation

“…8c, the electrode surface area remains practically invariant. A similar behavior was displayed by SERS spectra for pyridine, pyrimidine, pyrazine, and cyanide in a rather broad frequency range, with the spectra in question recorded by means of a multichannel optical analyzer [231]. In the absence of ER, on the other hand, SERS intensity for pyridine on a mechanically polished electrode or in the course of silver electrodeposition at the limiting diffusion current (Fig.…”

“…It was demonstrated, however, that even a single ORC in the case of silver in conditions close to these ensured observation of SERS from pyridine at silver [3]. Subsequent ER regimes were various: single and periodic rectangular anodic pulses of potential of different length [1,47,[53][54][55][56]; fast and slow linear potential scan with excursion to the surface oxidation or dissolution region [42,47,49,53,57] (see also papers by Benner et al in [28], Philpott et al and Owen et al in [32]) and combined regimes [57,58]. Shown was that ER under a laser beam in solutions containing anions that form salts with silver which are subjected to photoexcitation or even photolysis at excitation light wavelengths λ e (at first stages it was radiation of an ion argon laser at λ e = 514.5 nm that was used most frequently) ensured values of G that were several times (especially in the first cycle of ER) the "dark" ER [59][60][61] (see also papers by Philpott et al and Owen et al in [32]).…”

Optical second-harmonic generation from a monolayer of centrosymmetric molecules adsorbed on silver

“…It should be noted that we recorded the SH signal while making the silver electrode more negative at each step, since irreversible changes in the surface chemistry or structure seem to be induced for large reverse biases. 3 In the pyrazine solution, the maximal SH intensity was found to be -10 times as great as that originating from the roughened silver surface in the pure electrolyte. By way of comparison, the adsorption of pyridine gave 4 LBL-l2735 rise to a -50-fold increase in SHG.…”

Electric Field Assisted Growth of Highly Surface Enhanced Raman Active Gold Nanotriangles

“…2 The SERS phenomenon is often explained by the electromagnetic and chemical enhancement mechanisms. 3 The chemical enhancement mechanism involves charge transfer excitation 4 between the analyte molecules and the metal particles, whereas the electromagnetic mechanism is dominated by plasmon excitation leading to hot spots 5 around nano-sized metal particles by an increase in the local optical field. The magnitude of electromagnetic enhancement is highly dependent on the plasmon absorption of the substrate.…”