On the basis of different types of experiments, we develop implicitly the model of surfaceenhanced Raman scattering (SERS) of adsorbates on metal s u r f a c g . The long-range enhancement by resonances of the macroscopic laser and Stokes field is separated quantitatively from the metal eledmn-mediated resonance Raman effect. The latter mechanism proceeds b y increased electron-photon coupling at an atomically rough surface and by temporary charge transfer to orbitals of the adsorbates. This

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... el can account for the chemical spedficity and vibrational selectivity of SERS and (partly) for the SERS specificity of the various metals. Contents A Ofto el al 6.2.2. EELS of CO/Ag 6.2.3. Excitation profiles of SERS 6.2.4. Different Esites on cold-deposited copper 6.3. Screening at smooth surfaces 6.4. Increased surface-electron-photon coupling 6.5. Non-locality 6.6. The 'SE% specificity' of various metals 7. Summary 8. Literature review References Yamada H 1981 Appl. Spcctrorc. Re*. 17 227 Birke R L and Lombmdi J R 1982 Advances in Laser Spectmacopy m1 1, ed B Garetz and J R Dornhaus R 1982 Springer T~a c t t in Modem Physics vol 22 (Berlin: Springer) p 201 Cooney R P, Mahoney M R and McQuillan A J 1982 Aduancea in h j m r e d and Raman Spec-Marinyuk V V, Lazarenk+Manevich R M and Kolotyrliin Ya M 1982 Advances in Physical Ueba H, Ichimura S and Yamada H 1982 Swf, Sei. 119 433 Chang R K and Furtak T E (eds) 1981 Snrface-enhanced Raman Scattering (New York: Plenum) Furtak T E 1984 Advances in Laser Spcctroreopy "012, ed B Garetz and J R Lombsrdi (Chichester. Wiley) p 175 Schatz G C 1984 Acc. Chrm. Res. 17 370 Otto A 1984 Light Scattering in Solid3 "014, ed Cardona M and 0 Gimtherodt (Berlin: Springer) Arya K and Zeyher R 1984 Light Scoltcring in Solids ml 4, ed M Cardona and G Ghtherodt Wok" A 1984 Solid State Phyr. 38 223 Metiu H 1984 Pmg. Swf. Sci. 17 153 York: Academic) Lombardi (Philadelphia. PA: Heyden) p 143 tmscopy "019, ed R E Hester and R J Clark (London: Heyden) & 4 Chemistry ed Ya M Kolotpkin (Moscow: Mir) c h 6 (Berlin: Springer) ch 7 Ishida H, Fukuda H, Katagiri G and khitani A 1986 Appl. Spectrose. 40 322 Rubim J C, Kannen G, Schumacher D, Diinnwald J and 0 t h A 1989 Appl. Swf. Sei. 37 233 Lyon S A and Worlock J M 1983 Phyr. Rev. L d f . 51 593 Ertiirk U, P e t t d m f e r C and Otto A 1986 J. Elcctmn Spcclioae. Rclat. Phenom. 38 113 Crawford 0 H 1988 J. Chem. Phya. 89 6017 Hayashi S and Samejima M 1984 Swf. Sci. 137 442 T-g J C, Kirtley J R a n d Theiss T N 1980 Solid S i d e Commun. 35 667 Barber P W, Chang R K and Massoudi H 1983 Phyr. Rev. Lett. 50 Barber P W, Chang R K and Massoudi H 1983 Phyr. Rev. Lett. 50 997 Kovacs G J, Loutfy R 0, Vincett P S , Jennings C and Aroca R 1986 Longmsir 2 689 Notholt J and Ludwig P K 1988 Chem. Phys. L d f . 143 609 Mrozek I unpublished M r a e k I, Pettenkofer C and Otto A 1990 Swf. Sci. 238 192 M r a e k I, Bornem-T and Otto A 1988 Swf. Sei. 204 358