Enhancement, surface electromagnetic

Instrumentation. In order to employ local enhancement of infrared absorption by surface plasmon polaritons that cause locally enhanced surface electromagnetic fields, a suitable optical arrangement is needed [295]. Surface enhanced infrared absorption spectroscopy can also be observed in the transmission mode [285, 296]. However, since no application of this approach in spectroelectrochemistry has been reported so far, it is not discussed further. 

The possibility of utilizing the surface electromagnetic field to enhance the Raman scattering from overlayers on metals in an ATR configuration was proposed before the SERS era by Chen, et 375,376 predicted, for silver, enhancements of about 300 when... 

SEMPA Scanning Electron Microscopy with Polarisation Analysis, 37 SERS Surface Enhanced Raman Scattering, 32 SEW Surface Electromagnetic Waves Spectroscopy, 40 SEXAFS Surface EXAFS, 49... 

SERS is an interface-sensitive technique, with molecules adsorbed in the first layer at the surface showing the largest enhancements. However, electromagnetic enhancement has a long-range property (i.e., it decays exponentially with increasing distance from the surface, 1-10 nm) [45-48], which predicts that SERS does not require the adsorbate to be in direct contact with the surface but rather within a certain sensing volume. 

Fig. 17a, the surface electromagnetic field can be ca. 17 times as high as that in free space and the fluorescence intensity can be enhanced up to eightfold [119]. With regard to silver as the other metal substrate that plays a major role in SPR-based fluorescence applications and a bovine serum albumin-(BSA-) biotin/avidin multilayer system for distance adjustment. Cotton and co-workers could show that a monolayer yields only an 8-fold enhancement of the fluorescence while 6 layers increased the intensity gain to 15-fold (Fig. 17b) [118]. 

Raman enhancement can take place by either increasing the electric field ( ) experienced by the molecule (electromagnetic enhancement) or by changing the molecular polarizability of the adsorbate (chemical enhancement). The electromagnetic enhancement mechanism is explained by a phenomenon known as surface plasmon resonance. Surface plasmons are oscillations of conduction band electrons at a metal surface. At the surface... 

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