Magnetization induced

The intensity of the magnetic field produced by eddy current is depended on electrical conductivity and magnetic permeability of the studied area. In case of a uniform structure, when the conductivity of the material is high, the intensity of the induced magnetic field is big and signal received by probe Hp is small. 

Structure defects decrease conductivity of the studied material, and then the intensity of the induced magnetic field is small and the signal received by the probe Hp is big (Fig.2). Low conductivity of austenite is a defects of the structure in case of residual austenite in the martensite structure, which with regard to the magnesite structure is as 1 5. Eddy currents produced in the studied area are subject to excitation in effect of small conductivity of austenite grains in the structure of the studied material. 

The first equation (1) is the equation of state and the second equation (2) is derived from the measurement process. Finally, G5 (r,r ) is a row-vector that takes the three components of the anomalous ciurent density vector Je (r) = normal component of the induced magnetic field. This system is non hnear (bilinear) because the product of the two unknowns /(r) and E(r) is present. 

Pedersen J B 1979 Theories of Chemicaiiy induced Magnetic Poiarization (Odense Odense University Press)... 

Lepley A R and Closs G L (eds) 1973 Chemically Induced Magnetic Polarization (New York Wiley) An early summary of research In the field of CIDNP. 

Muus L T (ed) 1977 Chemically Induced Magnetic Polarization Proc. NATO Advanced Study Institute (Sogesta, Urbino, Italy, April 17-30, 1977) (Boston, MA Reidel)... 

FIGURE 13 6 The induced magnetic field of the elec trons in the carbon-hydrogen bond opposes the external magnetic field The resulting magnetic field ex perienced by the proton and the carbon is slightly less than Xr,... 

Acetylenic hydrogens are unusual in that they are more shielded than we would expect for protons bonded to sp hybridized carbon This is because the rr electrons circulate around the triple bond not along it (Figure 13 9a) Therefore the induced magnetic field is parallel to the long axis of the triple bond and shields the acetylenic proton (Figure 13 9b) Acetylenic protons typically have chemical shifts near 8 2 5... 

FIGURE 13 8 The induced magnetic field of the tt elec trons of (a) an alkene and (b) an arene reinforces the applied field in the regions where vinyl and aryl protons are located... 

FIGURE 13 9 (a) The TT elec trons of acetylene circulate in a region surrounding the long axis of the molecule (b) The induced magnetic field associated with the tt electrons opposes the applied field and shields the protons... 

FIGURE 13 10 More shielded (red) and less shielded (blue) protons in (a) [18]annulene and (b) [16]annulene The induced magnetic field associated with the aromatic ring current in [18]annulene shields the inside protons and deshields the out side protons The opposite occurs in [16]annulene which is antiaromatic... 

Oriented In-Plane Texture. In this kind of film the properties (H and in the various in-plane directions (texture and nontexture directions) are different. The texture of the film can be supported by the texture of the substrate and the crystal lattice can be smaller in the texture direction than in the transverse direction. This can be the source for strain-induced magnetic anisotropy (magnetostriction). It is also found that the crystal is aligned in the texture direction (92). 

Flux density is calculated as the permeability of free space times the sum of the magnetic-field intensity and the induced magnetization... 

The magnetic susceptibility of a material (%, volume susceptibility) is dimensionless and is defined as the ratio of induced magnetization to magnetic field intensity. It is expressed as... 

Fig. 5.16. The relative, shock-induced magnetization change is determined at a given pressure by the ratio of peak current to that at full magnetization change. Various sensitivities with pressure are indicated in agreement with static high pressure data. Offsets at zero magnetization change are typical and may be due to magnetic or mechanical effects (after Edwards [90E01]).

G) The induced magnetic field associated with the tt electrons opposes the applied field and shields the protons. 

Figure 4-9. (Ai Precessing moment vectors in field tfo creating steady-state magnetization vector Afo. with//i = 0. (B) Immediately following application of a 90° pulse along the x axis in the rotating frame. (C) Free induction decay of the induced magnetization showing relaxation back to the configuration in A.

Now with Hx turned off, the induced magnetization must relax to its steady-state value. This is the free induction decay phase. Figure 4-9C shows an intermediate stage in the FID is increasing ftom zero toward Mq, and My is decreasing toward zero. As we have seen, relaxes with rate constant l/Ti, and My relaxes with rate constant l/T 2. 

Figure 15.14 The origin of aromatic ring-current. Aromatic protons are deshielded by the induced magnetic field caused by delocalized tt electrons circulating in the molecular orbitals of the aromatic ring.

Induced magnetic field because of ring current... 

For a review of the application of CIDNP to rearrangement reactions, see Lepley, A.R. in Lepley Gloss Chemically Induced Magnetic Polarization, Wiley NY, 1973, p. 323. 

Focussing on terms linear in the applied field B, the induced magnetic field at the field point R obtains as the expectation value of B "(R, Ro,B) with respect to the first order wave function corresponding to eq.(6), yielding... 

Diamagnetism Substances that have no unpaired electrons are diamagnetic. When placed in an applied magnetic field, their induced magnetic fields oppose the applied magnetic field. 

Parami netism Magnetic behavior of nuclei that contain unpaired electrons. When such substances are placed in a magnetic field, the induced magnetic field is parallel to the applied magnetic field. 

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