SURFACE-ENHANCED RESONANCE RAMAN-SPECTROSCOPY OF FLAVINS ON SILVER NITRATE-MODIFIED CU AND FE AS WELL AS CU-ZN-PB AND FE-C-CR-NI SURFACES

Surface-enhanced resonance Raman spectroscopy (SERRS) of riboflavin, f lavin adenine dinucleotide (FAD), and flavin mononucleotide (FMN ) on Cu, Cu-Zn-Pb, and Fe as well as Fe-C-Cr-Ni has been performed by means of the modification of these substrates with silver nitrate. It is fo und that the SERR spectrum of a flavin molecule on the alloy Cu Zn-Pb is different from that on the pure Cu, and this is also the case for a flavin molecule on the alloy Fe-C-Cr-Ni and on pure Fe. This result i ndicates possibly that Zn, rather than Cu, and Ni or Cr, rather than F e, in the alloys also interact with the flavin molecules. In addition, the three flavins on the same supporting metal surfaces also exhibit some differences in the SERR spectra. This result implies an involveme nt of the side chains of the flavin molecules in the enhancement. The SERR spectra of the three flavins are compared with their resonance Ra man (RR) spectra. On the basis of our experimental results, a direct i nteraction of N--5 and possibly also O--4 in the flavins with silver i s suggested. The general effectiveness of this method for obtaining SE RS is demonstrated, and the enhancement mechanism of these substrates is also briefly discussed.