Surface electromagnetic waves

Surface electromagnetic waves or surface polaritons have recently received considerable attention. One of the results has been a number of review articles1, and thus no attempt is made here to present a comprehensive review. These review articles have been concerned with the surface waves, per se, and our interest is in the use of surface electromagnetic waves to determine the vibrational or electronic spectrum of molecules at a surface or interface. Only methods using optical excitation of surface electromagnetic waves will be considered. Such methods have been the only ones used for the studies of interest here. 

Surface electromagnetic waves (SEW) on a metal-vacuum interface (often called surface plasmons) are discussed to demonstrate the essential features of SEW. SEW are surface waves in the sense that the electric and magnetic fields decay exponentially as one moves away from the surface, either into the metal or into the vacuum. Figure 1 shows the coordinate system we shall use. The metal-vacuum interface is the z = 0 plane, and the metal occupies the z < 0 half-space. The direction of propagation is the positive x-directi on. The metal has a... 

Figure 1. Coordinate system for surface electromagnetic waves on a metal-vacuum...

Figure 3. Dispersion curve for a surface electromagnetic wave on a gold vacuum...

Figure 5. Decay lengths for the electromagnetic field of a surface electromagnetic wave on a Cu-vacuum interface. The right-hand scale is for the decay length into the Cu and the left-hand scale for the decay length into vacuum.

Figure 7. The surface electromagnetic wave transmission between two prisms separated by 10 cm for (a) one monolayer of CugO on Cu and (b) five monolayers...

Figure 8. ATR method for exciting surface electromagnetic waves by using a single prism as developed by A. Otto (11). The angle of incidence of the light on...

Figure 10. The two prism method for surface electromagnetic wave spectroscopy as developed by Schoenwaid, Burstein, and Elson (14)...

Figure 20. Propagation distance of surface electromagnetic waves on GaAs as a function of carrier concentration for a frequency of 84 cm 1 (23)...

Figure 21. Propagation distance of surface electromagnetic waves on SrTiO,. The solid curve is calculated from the two points measured with a molecular laser (24).

Figure 4. A typical experimental configuration of surface electromagnetic wave propagation spectroscopy. A surface wave is launched along the surface of a metal using a coupling prism separated by an air gap. The light is coupled out to a detector through another prism.

Surface plasmons, or surface plasmon polaritons, are surface electromagnetic waves that propagate inside a metal along a metal/dielectric (or metal/ vacuum) interface their excitation by light is surface plasmon resonance (SPR) for planar surfaces or localized surface plasmon resonance (LSPR) for nanometer-sized metal particles. 

Surface plasmons (SPs) are surface electromagnetic waves that propagate parallel along a metal/dielectric interface. For this phenomenon to occur, the real part of the dielectric constant of the metal must be negative, and its magnitude must be greater than that of the dielectric. Thus, only certain metals such as gold, silver, and aluminum are usually used for SPR measurements. The dispersion relation for surface plasmons on a metal surface is ... 

Another interesting variant of the total reflection technique is the so-called Surface Electromagnetic Wave Spectroscopy (SEWS), which consists of the generation of a surface plasmon on a substrate by frustrated total internal reflection in a prism located a few microns from the surface. This plasmon is decoupled by a second prism. Some interesting data relating to surface modes on alumina have been reported with this technique [30]. 

Photonic band gap (PEG) materials represent a class of composites that are designed to monitor the properties of photons in much the same manner as semiconductors manipulate the electrons properties. These composites have been developed from ordered arrays of self-assembled nanometer-sized polyst3a ene spheres that have been repeatedly encapsulated with various polymeric systems. However, it has been recognized that PEG materials also support surface electromagnetic waves-optical modes that propagate at the interface of a PEG crystal [193]. 

Surface electromagnetic waves (SEWs) in PCs have also been used for sensing particularly in ID PCs. They are excited at certain incidence and are sensitive to the layer adjacent to the surface [108-110]. Although it is possible to excite SEWs in PCs, coupling through a prism is preferable in order to observe them in measurable incidence angles (Fig. 12). 

Robertson WM, May MS (1999) Surface electromagnetic wave excitation on one-dimensional photonic band-gap arrays. Appl Phys Lett 74 1800-1802... 

Shinn M, Robertson WM (2005) Surface plasmon-like sensor based on surface electromagnetic waves in a photonic band-gap material. Sensors Actuators B Chem 105 360-364... 

---