Surface-enhanced Raman spectroscopy distance dependence

M., Cass, A.E.G., and Cohen, L.F. (2006) A note on distance dependence in surface enhanced Raman spectroscopy. Chemical Physics Letters, 430,173-176. 

Surface-enhanced Raman spectroscopy (SERS) provides a means of obtaining the Raman spectmm of a monolayer. Although this method requires careful preparation of a roughened surface (necessary for intensity enhancement), and the absorbance may vary from sample to sample, it is very sensitive to the functionalities located close to the metal surface. The enhancement factor depends inter alia on the distance between the functional group and the metal surface on one hand and the surface coverage on the other. A typical distance at which the enhancement factor decreases to half of its initial value in a well-packed gold-thiol monolayer is about 3.5-7. This technique provides useful... 

Thin film of metal clusters enable other types of surface enhancement, one of these is the surface enhanced infrared absorption (SEIRA) spectroscopy. The enhancement is an addition of electromagnetic field effects and chemical effects, therefore highly dependent on the distance to the cluster layer and on the nano-structure of the cluster layer. In fact most studies done point out that the effect is very short ranged and only applicable to the first monolayer adsorbed to the surface. Compared to standard infrared spectroscopy and Surface enhanced Raman scattering SEIRA has a remarkable signal to noise ratio and the... 

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