Raman spectroscopy of p-hydroxybenzoic acid aqueous solution and surface-unenhanced Raman scattering on silver colloid with ultraviolet excitation

Surface Raman scattering studies on the adsorption of p-hydroxybenzoic acid at Au electrodes with ultraviolet excitation

“…It is notable that UV Raman spectroscopy makes it possible to obtain the Raman signal of PHBA in aqueous solution as exhibited in Fig. 1(a), though the NIR or visible Raman spectrum of PHBA in aqueous solution is hardly measurable due to the quite low solubility [20]. Since the intensity of any background fluorescence is decreased and the intensity of the Raman signals is increased using UV excitation, compared to visible and NIR excitation, this may imply that the Raman scattering cross section of PHBA molecules is probably larger, due to a UV resonance enhancement.…”

“…In particular, the high-quality Raman spectrum of PHBA aqueous solution, which could not be observed with visible and NIR excitations, due to the low concentration, can, however, be measured with ultraviolet (UV) excitation at 325 nm [20].…”

Temporal Electronic Structures of Nonresonant Raman Excited Virtual States of P-Hydroxybenzoic Acid

“…In the following theoretical calculation, we first used the RHF/6-31 G methods to optimize the structure in order to initiate its force constants and molecular structural parameters with reference to the literature. [17,18] These data are then employed to refine the force constants until the calculated normal mode wavenumbers are well fitted to the observed ones, which are obtained from the experimental Raman spectra. The Raman spectra of p-hydroxybenzoic acid were detected by a Renishaw RM-1000 microconfocal spectrophotometer equipped with a CCD detector.…”