Spinning axis

Spatially localized NMR spectroscopy was performed using a sample composed of a monoolein-D20 dispersion forming a cubic liquid-crystalline phase [41]. The spectra were selected from a slice of 300-pm thickness. The direction of the gradient was along the spinning axis. A spectral resolution was obtained that had never been observed before when selecting the whole volume of the sample. 

During the p decay process, there exists anapole moment along the spin axis of the parent nuclei [1]. The anapole moment presents a new kind of dipole moment which is invariant under time reversal and odd under parity. A pseudoscalar p( V x H. ct) exists between the anapole moment and the spin of the emitted electrons, where p is the interaction strength. This interaction breaks parity conservation. 

Fig. 1. Plot of the orientations of director and spinning axis of a rotating sample w.r.t. the external magnetic field.

Processional motion. Consider a spinning top. It also performs a slower waltz like motion in which the spinning axis of the top moves slowly around the vertical. 

Alignment between spin axis and spatial velocity for Crab and Vela pulsars (see for example Lai et al. 2001)... 

Nuclei with spin I > are not, as a rule, perfectly spherical distributions of charge, as may be shown by quite general quantum mechanical symmetry considerations (89). All nuclei possess the spin axis as a sym-... 

Here cto is the isotropic shift (1/3 [cti, 0-21 -1- ct3,]) and tree is the projection of the chemical shift tensor along the spinning axis and defined analogously to Eq. (3). In general this latter term produces a powder pattern when summed over nuclei at all orientations. However, when cos 0 = l/J3, the powder pattern collapses and only the isotropic value remains, i.e., CTjj/ = 0-5,. If this magic angle is misset by e radians, then (9)... 

When exposed to a static magnetic field B0, a spinning nucleus behaves like a gyroscope in a gravitational field. As illustrated by Fig. 1.2, the spin axis - which coincides with the magnetic moment vector p - precesses about B0. The frequency of precession, v0, is known as the Larmor frequency of the observed nucleus. 

The simplest bound nuclear system, the deuteron, consists of a neutron and a proton. The deuteron is known to have a quadmpole moment, 0.00286 barns, which tells us that the deuteron is not perfectly spherical and that the force between two nucleons is not spherically symmetric. Formally, we say the force between two nucleons has two components, a spherically symmetric central force and an asymmetric tensor force that depends on the angles between the spin axis of each nucleon and the line connecting them. 

Figure Al.l A schematic representation of an electron. The spin axis is designated by a vector, which also shows the direction of the magnetic moment.

The Earth s orbital chirality (EOC) is mainly created by both the Earth s right-handed helical rotation around its spin axis and the Earth s right-handed helical revolution around the Sun [8]. Finally, spiral galaxies show axial symmetry and an intrinsic 2D chirality [9]. 

Figure 3. Schematic of the spinner device showing two possible ways in which the correct magic-angle setting of the inclination of the spinning axis to the magnetic field axis may be obtained by continuous adjustment (13J...

For example, a spin- /2 nucleus can be viewed as having two quantum states one with the spin axis at a 45° angle to the external magnetic field and one with the spin axis at a 135° angle to the external field. A spin-1 nucleus can be viewed as having three possible states 45°, 90°, and 135°. In this book we will be concerned primarily with spin- /2 nuclei. 

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