Electromagnetic wave electric field

Most of the experiments discussed in this book are performed using continuous wave or nanosecond-pulsed lasers at I < 109 W/cm2 intensities, which correspond to electromagnetic radiation electric field strengths of < 9 x 105 V/cm. Such electric fields are weak relative to typical intramolecular field strengths, ° = 1 a.u. = 5.14 x 109 V/cm and are appropriately treated perturbatively (see Sections 6.1.2 and 6.5.3). 

The last attribute of tire electromagnetic field we need to discuss is wave polarization. The nature of tire transverse field is such tliat tire oscillating field disturbance (which is perjDendicular to tire propagation direction) has a particular orientation in space. The polarization of light is detennined by tire time evolution of tire direction of tire electric field... 

The interaction of electromagnetic radiation with matter can be explained using either the electric field or the magnetic field. For this reason, only the electric field component is shown in Figure 10.2. The oscillating electric field is described by a sine wave of the form... 

The electric field associated with this electromagnetic wave has two notable characteristics which distinguish it from the incident beam and make it useful... 

A diatomic molecule placed in an electric field of the type present in an electromagnetic wave experiences an induced dipole M at any instant due to the displacement of the electrons with respect to the relatively massive nuclei under the influence of the applied field E. 

In the theoretical section above, the nonlinear polarization induced by the fundamental wave incident on a planar interface for a system made of two centrosymmetrical materials in contact was described. However, if one considers small spheres of a centrosymmetrical material embedded in another centrosymmetrical material, like bubbles of a liquid in another liquid, the nonlinear polarization at the interface of a single sphere is a spherical sheet instead of the planar one obtained at planar surfaces. When the radius of curvature is much smaller than the wavelength of light, the electric field amplitude of the fundamental electromagnetic wave can be taken as constant over the whole sphere (see Fig. 7). Hence, one can always find for any infinitely small surface element of the surface... 

To obtain a clear understanding of electrodynamic bonding, start with the field of a static electric dipole. Then, let the dipole oscillate so it emits electromagnetic waves (photons). Consider what happens when the emitted field envelopes another dipole (London, 1937). Finally, determine the factors that convert neutral molecules into dipoles (that is, their polarizabilities). 

X-ray diffraction. The mechanism by which atoms diffract or scatter electromagnetic radiation via the coupling of the electron cloud of the atom to the incident oscillating electric field was discussed in the section on SERS. The X-rays scattered by an atom are the resultant of the waves... 

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