Nuclei quantized orientation

To picture the spatial distribution of an electron around a nucleus, we must try to visualize a three-dimensional wave. Scientists have coined a name for these three-dimensional waves that characterize electrons they are called orbitals. The word comes from orbit, which describes the path that a planet follows when it moves about the sun. An orbit, however, consists of a specific path, typically a circle or an ellipse. In contrast, an orbital is a three-dimensional volume for example, a sphere or an hourglass. The shape of a particular orbital shows how an atomic or a molecular electron fills three-dimensional space. Just as energy is quantized, orbitals have specific shapes and orientations. We describe the details of orbitals in Section 7-1. 

A related RF technique to NMR is nuclear quad-rupole resonance (NQR). In NQR, transitions between nuclear quadrupole levels of nuclei in a solid material are induced by the applied radiation. The electric field gradients in the solid orient the quad-rupolar nuclei I>1/2) and give rise to quantized energy levels that yield transitions in the MHz range. FT-NQR spectroscopy measures these splittings and the relaxation times by free induction decay or various pulse echo experiments. FT-NQR spectroscopy provides information about the local environment around the quadrupolar nucleus in a crystal. 

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