Surface-enhanced hyper-Raman and surface enhanced resonance hyper-Raman scattering of molecules adsorbed to silver electrode surfaces.

摘要

Surface enhanced hyper-Raman scattering (SEHRS) spectra were observed for pyridine with an increase in the signal to noise ratio (S/N) by a factor of 10 over previously reported SEHRS spectra for this molecule. In addition, normal hyper-Raman scattering (NHRS) spectra were calculated using a semiempirical PPP molecular orbital approach with an empirically derived force field for pyridine. Both bulk and surface NHRS spectra are calculated. The calculated surface NHRS spectra agree well with experiment. The SEHRS enhancement factor (EF) was found to be on the order of 10;SEHRS spectra are reported for pyrazine, pyrimidine, and pyridazine for the first time. Force fields were developed for these molecules as well, and spectra were calculated as they were for pyridine. Because pyrazine has D;No SEHRS spectra could be observed for piperidine (saturated pyridine) even though intense surface enhanced Raman scattering (SERS) spectra were observable. This showed that the nonlinear optical properties of the molecule were important to observing SEHRS spectra.;SEHRS spectra of 2,2