Nuclear spin number

Amorphous orientation average Crystalline orientation average Nuclear spin number Scattered intensity Scattered intensity Transmitted intensity... 

TABLE 3.1 Type of nuclear spin number, /, with various combinations of atomic mass and atomic number. 

The fluorine atom has a nuclear spin number of 1/2, similar to that of hydrogen, and is therefore snitable for NMR measurements, giving narrow lines. The other halogens have nuclear spin numbers > 1 /2 (3/2 for chlorine and bromine, 5/2 for iodine), and so are unsuitable for NMR studies. 

For an atom with a nuclear spin number /, there are 2 / + 1 quantized nuclear energy levels 1),... (/ - 1), /. These levels are practically equal... 

We can determine how many allowed spin states there are for a given nuclide by multiplying the nuclear spin number by 2 and adding 1. For a spin-Vx nuclide, there are therefore 2 (TA) -F 1 = 2 allowed spin states. 

The two spectra in Figures 6.23 and 6.24 demonstrate coupling between and P. In the first compound, shown in Figure 6.23, the carbon atom of the methyl group at about 12 ppm is split by one adjacent phosphorus atom into a doublet with a coupling constant equal to 56.1 Hz (919.3 -863.2 = 56.1 Hz). Notice that the n -h1 Rule predicts how the pattern will appear (doublet). The nuclear spin number for phosphorus is the same as for a proton and for a fluorine atom (. This interaction is an example of one-bond coupling (V). 

Nuclear resonance spectroscopy is based on the nuclear resonance effect, which can occur only in nuclei containing odd numbers of protons and/or neutrons in so far as such nuclei have intrinsic magnetic moments. In other words, NMR is theoretically applicable for nuclei with the nuclear spin number I larger than 0 however, practically only nuclei with 1 = 1/2 are those most used for NMR study since those with I > 1/2 possess electric quadrupole moments which broaden the line width and reduce the resolution of the spectra. 

The electric field gradient (EFG) is a ground state property of solids that sensitively depends on the asymmetry of the electronic charge density near the probe nucleus. The EFG is defined as the second derivative of the electrostatic potential at the nucleus position written as a traceless tensor. A nucleus with a nuclear spin number / > 1 has a nuclear quadrupole moment (Q) that interacts with the EFG which originates from the nonspherical charge distribution surrounding this nucleus. This interaction... 

The quadrupole interaction occurs only when the nuclear spin number /> 1/2 (eg, H, "B,... 

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