Magnetic dipole, contribution absorption

Solids give rise to the "wide-line" or (broad-line) spectra, because the local fields arising from nuclear magnetic dipole interactions contribute significantly to the total field experienced by a nucleus in the solid state. A measure of this direct spin-spin interaction is the spin-spin relaxation time T2 (see Sect. 12.2.1.3), which is much shorter in solids than in liquids, and thus gives rise to broader lines (of the order of 10-6 to 10 4 T, depending on the kind of nucleus). Now the contour of the absorption line provides information as to the relative position of the neighbouring nuclei. 

The i f f) contribution gives rise to the familiar electric dipole absorption responsible for a large part of electronic spectroscopy. The second term in the matrix element may be divided into a symmetric part, identifiable with the electric quadrupole interaction, and an antisymmetric part which is the magnetic dipole operator ... 

The derivations of 2 c were made with the assumption that only the induced electric dipole furnishes a contribution to the radiation. This is correct for a sphere with a radius smaller than 0 05 X. For larger particles one must take into account the electric moments of higher order and also induced magnetic moments. The theory has been extended in this manner by Mie while he also took into account the absorption of light by the particles. He showed that for spheres up to approximately the magnitude of X it is sufficient to deal with the induced electric dipole and quadrupole and the magnetic dipole. The formulae for the scattered light with the direction of vibration perpendicular and parallel to the plane of observation become respectively ... 

The first contribution to the induced electric dipole moment in O Eq. 11.74 from the time dependence of the magnetic field, w G, gives rise to two different observable properties. In the dispersive region, this property determines the optical rotatory power, or just optical rotation (OR) for short, and in the absorptive region it determines the rotational strength observed in electronic circular dichroism (ECD). 

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