Surface electromagnetic waves, absorption

Zhizhin, G., Morozov, N., Moskalova, M., Sigarov, A., Shomina, E., Yakovlev, V., and Grigos, V. (1980). Surface electromagnetic wave absorption on copper surfaces with Langmuir films using CO2 laser excitation. Thin Solid Films, 70 163 -168. 

Alternatively, various analytical methods based on SPR phenomenon have been developed, including surface plasmon field-enhanced Raman scattering (SERS) [7], surface plasmon field-enhanced fluorescence spectroscopy (SPFS) [8-11], surface enhanced second harmonic generation (SHG) [12], surface enhanced infrared absorption (SEIRA) [13], surface plasmon field-enhanced diffraction spectroscopy (SPDS) [14-18], Most of these methods take advantage of the greatly enhanced electromagnetic field of surface plasmon waves, in order to excite a chromophoric molecule, e.g., a Raman molecule or a fluorescent dye. Therefore, a better sensitivity is expected. 

These electromagnetic waves are very sensitive to any change in the boundary—for example, to the adsorption of molecules onto the metal surface. SPR has measured the absorption of material onto planar metal surfaces (typically Au, Ag, Cu, Ti, or Cr) or onto metal nanoparticles and is used in many color-based biosensor applications and lab-on-a-chip sensors. To observe SPR, the complex dielectric constants e1 of the metal and s2 of the dielectric (glass or air) must satisfy the conditions Re(ei) < 0 and > e21,... 

On metal surfaces, two additional selection mles apply. The first is that only vibrations perpendicular to the surface are HREELS active. This mle follows from two phenomena unique at metal surfaces " (i) Electromagnetic waves polarized perpendicularly to the plane of incidence (parallel to the plane of the surface) undergo a 180° phase shift upon reflection. That is, at the metal surface, the out-of-phase electric-field vectors of the incident and reflected waves cancel each other as a result, no field exists that can couple with dipoles that oscillate parallel to the surface, (ii) The dynamic dipole moment generated by an oscillator that vibrates in the surface-parallel direction is cancelled by that of its image dipole (Figure 1) hence, there the net dynamic dipole moment is zero. On the other hand, if the real dipole is oriented perpendicularly to the surface, its dynamic dipole moment is reinforced by that of its image dipole. This selection mle is the same as that for infrared reflection-absorption spectroscopy (1RAS).°... 

In the absence of tabulated or measured properties for a given surface, various options are available. The behavior of a surface can be computed based on fundamental theories, such as Maxwell s electromagnetic wave theory the surface characteristics can be assumed based on extrapolation from the behavior of similar surfaces a model of the surface behavior can be constructed based on simplified assumed surface characteristics or greatly simplified characteristics can be assumed to be accurate enough for use. In the third table in App. A (Table A.7.3), the spectral complex index of refraction data for a number of metals are listed (from Ref. 16), which can be used to determine the surface absorption, reflection, and transmission characteristics as discussed below. 

The RTE is a simplified form of the complete Maxwell equations describing the propagation of an electromagnetic wave in an attenuating medium. The simplified RTE does not include the effects of polarization of the radiation or the influence of nearby particles on the radiation scattered or absorbed by other particles (dependent scattering or absorption). For example, if polarization effects are present (as they are when reflections occur at off-normal incidence from polished surfaces or in reflections from embedded interfaces), then the analyst should revert to complete solution of the Maxwell equations, which is a formidable task in complex geometries Delineating the bounds of applicability of the radiative transfer equation is an area of active research. 

Spectroscopic techniques that employ electromagnetic radiation between vacuum UV energy ( 10-40 eV, 125-31 nm) and soft X-rays (40-1500 eV, 31-0.8 nm) and going on to hard X-rays (1500-105 eV, 0.8-0.01 nm) have also been of great importance in elucidating the electronic structure of complex materials [34]. It is well known that an electromagnetic wave can be scattered and/or absorbed when interacted with the surface of material. In the case of absorption, the X-ray beam intensity (/) is attenuated by the solid... 

Emissivity, absorptivity, reflectivity, and transmissivity are the key radiation properties. The relative magnitudes of a, p, and T depend not only on the material, its thickness, and its surface finish, but also on the wavelength of the radiation (Kreith, 1965). Nevertheless, the emission of electromagnetic waves is a property of the material only. 

From the general selection rule (1.27), it follows that, unlike the case of the transverse excitations = 0°), the longitudinal excitations (t = 90°) are nonradiative for any experimental geometry of experiment that is, they do not interact with the transverse electromagnetic wave. For ultrathin films, absorption of p-polarized radiation at the frequency close to surface mode produced by the so-called size effect (Section 3.2). 

Radiation is the transfer of thermal energy in the form of electromagnetic waves it occurs in processes of emission, reflectivity and absorptivity. The quantity of heat Qr radiated through a transparent gas layer from surface As at temperature Ts to surface Ao at temperature To, completely enclosing the first surface, is... 

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