文摘
The charge-transfer resonance of Raman measurements in nanosized semiconductor鈥搈olecule鈥搈etal interfaces as a function of the excitation energy with four models (Cu鈥揨nO鈥揚ATP鈥揂g, Cu鈥揂g鈥揚ATP鈥揨nO, Cu鈥揨nO鈥揂g鈥揚ATP, and Cu鈥揂g鈥揨nO鈥揚ATP assemblies) to describe this dependence provides a powerful tool to study the chemical mechanism of surface enhanced Raman scattering (SERS). We measured the SERS spectra of self-assembled p-aminothiophenol (PATP) molecule junctions at 488, 514, 633, and 785 nm excitation wavelengths. We followed changes at the molecule junctions during the conditioning and eventually effect of charge-transfer (CT) through molecule鈥揨nO interfaces. Our results demonstrate that the interaction between the semiconductor bands and molecular energy levels can lead to novel charge behavior. The typical ZnO-PATP interfacial electron鈥揾ole recombination causes an increase in the CT resonance enhancement of Raman scattering, which is mainly responsible for the drastic change in molecular polarizability. We also proposed a complementary interpretation of the mechanism responsible for the highly variable enhancement observed in SERS.