Highly-sensitive Raman spectroscopy to characterize adsorbates on the electrode

Theoretical calculation shows that ATR-surface-plasmon-polariton Raman spectroscopy is guile useful to increase Raman scattering intensity from adsorbates even on transition metals with higher intrinsic damping than silver. In fact, a remarkably large enhancement factor of ca. 300 was obtained for Raman band intensity from copper phthalocyanine (CuPc) on platinum, compatible with theoretical values only by assuming parallel orientation of the CuPc molecules on the platinum surface. Parallel orientation was also confirmed by a decreased depolarization ratio of the 1530 cm(-1) (A(1g)) band for thinner CuPc adlayers. Two different adsorbed slates for pyridine on optically flat silver surfaces were observed in an electrochemical environment for the first time. (C) 1997 Elsevier Science B.V.