Surface Enhanced Raman Spectroscopy of Pyridine on CdSe/ZnBeSe Quantum Dots Grown by Molecular Beam Epitaxy

Using surface enhanced Raman spectroscopy (SERS), we observed Raman enhancements (104-105) for pyridine molecules adsorbed on II-VI semiconductor quantum dots on (uncapped CdSe/ZnBeSe) produced by molecular beam epitaxy. When a monolayer of pyridine is adsorbed on these structures, excitation at 488 nm produces intense Raman spectra, a very large enhancement of the a1, b1, and b2 modes. This indicates the presence of charge transfer as a contributor to the enhancement. Furthermore, the excitation wavelength is in the vicinity of several interband transitions located both in the quantum dots and the wetting layer, and it is likely that these resonances also contribute to the enhancement factor.