Electromagnetic waves scale

Figure 1 Electromagnetic wave scale of DS applicability for complex materals.

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 1.3. Sketch of the polariton dispersion for a given direction K (notice the scale change to cover the entire Brillouin zone). The broken straight lines indicate the dispersion of the electromagnetic waves in the crystal far from the excitonic b transition. In the stopping band (hatched), only excitonic states with large wave vectors may be created, and the crystal reflection is "quasi-metallic .

The propagation of electromagnetic waves in bulk solid materials and in molecules is well understood. This understanding is appropriate for bulk EXAFS, for instance, but not necessarily for surface studies. The situation of a solid surface has only been studied recently in terms of atomic-scale phenomena, as is required by techniques such as photoemission. Although photons typically penetrate to a depth of about 1 fim into the metal surfaces of interest, the only important photon-induced excitations occur within the electron escape depth of about 5 to 10 A. Therefore, the shape of the electromagnetic fields should be known in this near-surface region of a few atomic layers. 

Fig. 1.1.2 Electromagnetic waves. Frequency (left) and wavelength (right) scales for optical, EPR, and NMR analysis. Adapted from [Krel] with permission from Publicis MCD.

Plane wave An electromagnetic wave with infinite transverse dimensions. It is an idealized model of a light beam where the finite transverse extent of a real beam is ignored for mathematical expediency this works well if the beam diameter is large on the scale of the wavelength. The planes of constant phase are parallel everywhere. 

ESR is a magnetic resonance method using microwave frequencies of the order of 10 GHz. This means that ESR has a different time scale compared to NMR (electromagnetic waves of the order of 100 MHz are common in most NMR spectrometers). A few examples of motional narrowing of line width, which is connected with the time scales will be discussed in Sect. 8. 

Portions of electromagnetic waves A, B, and C are represented below (not drawn to scale) ... 

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