Coherency vector total field

As mentioned before, a scattering particle can change the state of polarization of the incident beam after it passes the particle. This phenomenon is called dichroism and is a consequence of the different values of attenuation rates for different polarization components of the incident light. A complete description of the extinction process requires the introduction of the so-called extinction matrix. In order to derive the expression of the extinction matrix we consider the case of the forward-scattering direction, = 6fc, and define the coherency vector of the total field E = Eg + E. by... 

On timescales of less than or equal to that of spin-spin relaxation (T2) processes occur. T2 characterises the loss of phase coherence of the individual spin isochromats within the spin ensemble comprising the total magnetisation vector M0. A spin isochromat represents a group of spins that experiences the same homogeneous magnetic field and which, therefore, behaves in the same... 

An important phenomenon that can occur with electromagnetic waves is interference. If several waves are present, the total electrical field at any place and time is the sum of the electrical fields of each of the waves. If the field vectors point in the same direction and are appropriately in phase, they add up to a stronger field, which is called constructive interference if they point in opposite directions, they cancel each other, which is referred to as destructive interference. If the phase relationship between the different waves does not change over time, constmctive and destructive interference will lead to areas of high and low intensity, respectively. In that case, the waves are said to be coherent. 

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