Studies Of Temperature-Induced Surface Enhanced Raman Scattering And Ultraviolet Raman Spectroscopy

Surface Enhanced Raman Scattering (SERS) is sensitive for in situ studying of orientation of molecules adsorbed on the substrate and probing of interfacial phenomena. However, according to many factors involved, its enhancement mechanisms have not well understood yet. It is well known that temperature is an important factor influencing surface adsorption and reaction. In this paper, we report the temperature-induced SERS of a series of derivants of benzene in silver colloid, which is measured after cooling down to room temperature from different high temperature. We find that the influence due to heating is all kinds: The heating treatment induces the change of PHB A molecules' adsorbed states; Molecules' geometries and adsorbed states of PABA in silver colloid will all change after heating; Temperature-induced changes of OABA or MHBA in silver colloid aren't notable. But all the general intensities of SERS are enhanced after cooling from high temperature. We analyze the possible reasons inducing the changes in the spectra. On the basis of these experiments, it may be possible to further enhance intensity of SERS through heating the mixture of the sample solution and the silver colloid.Employing photons as probes, Raman spectroscopy is potentially an ideal technique for studying chemical structures and physical interface phenomena. The photons with ultraviolet (UV) frequency have high energy, which could induce resonance or near resonance transitions between electron energy levels o f molecules. Moreover, UV Raman can avoid the fluorescence. Due to those merits of UV Raman, we have obtained high-quality Raman spectra of some samples, mainly including derivants of benzene in aqueous solution, which are difficult to be observed at NIR or visible excitation. It's worthwhile to note that no SERS effect is observed for above-mentioned samples at UV excitation, and we call it Surface Unenhanced Raman Scattering (SUERS). The SUERS in UV region can be explained by the absence of bothsurface-plasmon resonance and charge transfer (CT) excitation. The surface-plasmon resonance condition can't be meet as concerning Ag in UV region. The photon energy of ultraviolet used in our experiments is about 3.8 ev (325 nm) and the CT excitation condition can't be satisfied.