The coupling constant, usually referred to as g, is a number that determines the strength of an interaction in physics. Generally, the Lagrangian or Hamiltonian of a system can be separated into a kinetic part and an interaction section. The coupling constant determines the strength of the interaction section with respect to the kinetic portion, or between two sectors of the interactive section. For example, the electrical charge of a particle is a coupling constant. NMR spectroscopy
In the NMR spectroscopy, the coupling constant is the measure of the interaction between different magnetically active atomic nuclei. In the NMR spectroscopy, the symbol J is usually used. The unit is in that case Hz.
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