Angular resolved raman spectra from pyridine adsorbed on silver electrodes

Light enhancement in surface-enhanced Raman scattering at oblique incidence

“…In contrast, the non-linearity in the thiophenol signal is quite different to silicon and therefore indicates anisotropic scattering from the SERS substrate. This observation is in keeping with previous results from a variety of SERS substrates [10,11]. Table 1 and was calculated according to the relationship given in the Appendix).…”

Tunable Surface-Enhanced Raman Scattering from Large Gold Nanoparticle Arrays

“…[13] Values for b are often dependent on the angle of observation and also the angle of incidence, which strongly influence the electric field intensity at metal surfaces. Raman scattering studies of adsorbates on smooth [19] and electrochemically roughened [20] silver surfaces have demonstrated marked changes in signal intensities as a function of observation angle, with a maximum between 558 and 608 relative to the surface normal. In comparison, the maximum half-angles from the objective lenses above are 158, 248, and 498 respectively, which correlate well with the considerable increases in G.…”

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

“…For example, spectra of non-amplified RS for pyridine on atomically smooth face (111) of single-crystal silver are excited by p light and not, by s light [44]. Conversely, SERS spectra for CN -ion on silver (naturally, roughened) are insensitive to the excitation light polarization [279], as are SERS spectra for pyridine generated at different angles of incident excitation light [300]. Nevertheless, invoking surface selection rules appears to be very helpful in some cases of in-depth probing into the structure, orientation, and nature of interactions of adsorbate molecule with metal, including those of value for establishing SERS mechanism.…”

“…The intensity of SERS, which was observed at slightly (to a depth of 1-2 monolayers) roughened surfaces of silver, gold, and copper electrodes, clearly depended on the angle between the scatter direction and a normal to the surface [300,301,307] (see also paper by Pettinger et al in [28]). The dependence has nothing to do with surface selection rules [298,299] and has the shape of one or several (after a deeper roughening [300]) intensity peaks whose position depend on neither the excitation and scattered light frequencies nor the adsorbate nature [307].…”

“…The fact of nearly full depolarization of SERS lines for various adsorbates [5,43,202,211,290,300,301] is akin to the question of surface selection rules in SERS spectra. Depolarization degree (see [16,302] for example) or the ratio between scattering light intensities measured for electric vectors parallel and normal to electric vector of excitation light is linked to components of the scattering tensor and vanishes in the case of spherically symmetrical molecule.…”