Evanescent electromagnetic field

This expression is useful for estimating of the radiation loss of an adiabatic taper with characteristic length L. Figure 13.7 shows the distribution of the evanescent electromagnetic field intensity in the vicinity of the taper for 0 = 0.2 pm 1,yao = 0.4 pm 1, L = 500 pm, and / 4 pm In agreement with illustration in... 

The adequate protein/polymer concentrations in feed for 3-D NPH exist for SPRi, because the evanescent electromagnetic field decays exponentially from the metal surface into the interacting medium as described above. The thickness of 3-D NPH-SA prepared over the concentration of 0.25/0.025% is too thick to monitor SPR interactions even at the center of spots. It is thought that different proteins have each optimum concentration for 3-D NPH immobilization method in the case of SPR measurements. 

If an incident laser light Eo interacts with the metal nanosphere, a collective movement of the electrons against the atomic cores of the metals - a so-called surface plasmon - is induced. The interaction of the surface plasmons and the incident laser light causes the so-called localized surface plasmon polaritons, resulting in an evanescent electromagnetic field E y, which is emitted fi-om the nanoparticle. The signal intensity achieved for SERS depends on the absolute square of the emitted field Egy, which can be simplified written as follows ... 

Fig. 4 Waveguide evanescent wave (EW) principle. Light is propagated through the waveguide (n ) and an electromagnetic field (called EW) is generated in the external medium (n2). The EW interacts with immobilized molecules that absorb energy, leading to attenuation in the reflected light of the waveguide...

For absorbers with magnetic dipole transitions, the evanescent magnetic field H leads to absorption of electromagnetic energy. Assuming equal magnetic permeabilities at both sides of the interface, the components of the evanescent field H at z = 0 are... 

Figure 2. Qualitative behavior of the field strength of the evanescent wave as a function of the angle of incidence (nt — 1,51 n -= 1.0). Contrary to the behavior of the electromagnetic field of normal" light the evanescent field comprises a longitudinal component, too. E and E respectively indicate the direction of polarization of the incident light.

A. The electromagnetic field decays evanescently into the adjacent media, with a decay length of several hundreds of nanometers. 

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