Classical and chemical effects of SERS from 2,2′:5,2″ terthiophene adsorbed on Ag-sols

✍ Scribed by Uttam K. Sarkar; A.J. Pal; Subhasis Chakrabarti; T.N. Misra

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 371 KB
• Volume: 190
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(92)86102-n

✦ Synopsis

Surface-enhanced Raman scattering (SERS) has been observed from 2,2' : 5,2" terthiophene (3T) adsorbed on Ag-sols. Experimental results suggest that the absorbed 3T molecules are anti but twisted and that the twist angle is smaller in the surfaceadsorbed state than in solution. The first-layer effect, i.e., maximum enhancement when a monomolecular layer of 3T is adsorbed on silver particles, has been observed for the first time in such SERS active surfaces. A charge-transfer model has ken shown to contribute to this effect. On the other hand, the Raman excitation frequency dependence ofthe enhancement suggests a significant classical electromagnetic contribution to SERS in sol.