Direct observation of surface-enhanced Raman scattering in ZnO nanocrystals

• Published in: Journal of Raman spectroscopy Vol. 40; no. 8; pp. 1072 - 1077
• Main Authors: Wang, Yanfei, Ruan, Weidong, Zhang, Junhu, Yang, Bai, Xu, Weiqing, Zhao, Bing, Lombardi, John R.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.08.2009
• Subjects: 4-mercaptopyridine; Adsorption; Nanocrystals; Plasmons; Raman scattering; Raman spectroscopy; Semiconductors; Surface chemistry; surface-enhanced Raman scattering; Zinc oxide; ZnO nanocrystals
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.2241

We have been able to observe the surface‐enhanced Raman scattering (SERS) from 4‐mercaptopyridine (4‐Mpy) molecules adsorbed on ZnO nanocrystals, which display 103 enhancement factors (EFs). An excitation wavelength‐dependent behavior is clearly observed. Another molecule BVPP is also observed to have surface‐enhanced Raman signals. The chemical enhancement is most likely responsible for the observed enhancement, since plasmon resonances are ruled out. The research is important not only for a better understanding of the SERS mechanism, but also for extension of the application of Raman spectroscopy to a variety of adsorption problems on a semiconductor surface. Copyright © 2009 John Wiley & Sons, Ltd. The surface‐enhanced Raman scattering (SERS) from 4‐mercaptopyridine molecules adsorbed on ZnO nanocrystals was observed. The enhancement factor (EF) was estimated to be 103. An excitation wavelength‐dependent behavior was clearly observed. The chemical enhancement is most likely responsible for the observed enhancement.