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In nuclear chemistry and nuclear physics, J-couplings (also called spin-spin coupling or indirect dipole–dipole coupling) are mediated through chemical bonds connecting two spins. It is an indirect interaction between two nuclear spins that arises from hyperfine interactions between the nuclei and local electrons. [1]
A J-coupling is an interaction between nuclei containing spin. J-couplings are also known as scalar couplings. This interaction is mediated through bonds, in contrast to dipole interactions, which are mediated through space. Typically, we consider the J-coupling to be a weak interaction, in comparison to the Zeeman interaction.
The coupling constant is simply the difference, expressed in Hz, between two adjacent sub-peaks in a split signal. For our doublet in the 1,1,2-trichloroethane spectrum, for example, the two subpeaks are separated by 6.1 Hz, and thus we write 3Ja-b = 6.1 Hz.
One is called j-j coupling, and the other is called L-S coupling. The j-j coupling scheme is used for heavy elements (Z > 40), and the L-S coupling scheme is used for the lighter elements. L-S coupling also is called R-S or Russell-Saunders coupling.
Definition. J or scalar coupling between magnetic nuclei (otherwise termed nuclear spins) is coupling via the intervening network of chemical bonds and depends on interaction between the nuclear spins and bonding electron spins. Introduction.
J-coupling, also known as scalar coupling, arises from nuclear magnetic moments in the same molecule affecting each other through the electron cloud, which is shared among atoms due to the molecular bonds in the molecule.
The coupling constant, J (usually in frequency units, Hz) is a measure of the interaction between a pair of protons. In a vicinal system of the general type, H a-C-C-H b then the coupling of H a with H b, J ab, MUST BE EQUAL to the coupling of H b with H a, J ba, therefore J ab = J ba.
