Thursday June 30, 2005
Friday July 1, 2005

"SERS and SPM techniques"
Ms. Rosa Lopez
Max-Planck-Institut für Biochemie

The origin of the enhancement of the Raman signal in Surface-Enhanced Raman Scattering (SERS) has been extensively discussed [1-2]. In the majority of the works, the relative SERS intensities are analyzed on the basis of the electromagnetic mechanism (EM), on the contrary, in very scarce papers the SERS is analysed on the basis of an alternative charge transfer (CT) enhancement mechanism [3]. SERS is therefore large only for special systems, such as pyridine on rough silver surfaces [4]. On contrast, at smooth metal surfaces there is at maximum only a very weak surface enhancement. This limitation can be surmounted by employing SPM techniques where an AFM or STM tip is used to increase the Raman scattering from molecules adsorbed at a smooth surface located underneath the tip [5-7]. This poster presents possibilities of SERS using SPM techniques and illustrates how important to the understanding of the SERS mechanism is probing SERS signals of adsorbed molecules in the near field. References: [1] M. Fleishmann, P.J. Hendra, A.J. McQuillan, Chem. Phys. Lett. 26, 163 (1974). [2] D.L. JeanMaire, R.P. Van Duyne, J. Electroanal. Chem. 84, 1 (1977). [3] M. Moskovits, D.P. DiLella, K.J. Mainard, Langmuir 4, 67 (1988). [4] J.F. Arenas, I. López Tocón, J.C. Otero, J.I. Marcos, J. Phys. Chem. 100, 9254 (1996). [5] V. Deckert, D. Zeisel, R. Zenobi, Anal. Chem. 70, 2646 (1998). [6] B. Pettinger, G. Picardi, R. Schuster, G. Ertl, Electrochemistry 12, 942 (2000). [7] A. Hartschuh, N. Anderson, L. Novotny, J. Microsc. 210, 234 (2003).