Dipolar field effects described by boson operators techniques: The case of intermolecular multiple-quantum coherences in liquids

Dipolar couplings between macroscopically distant spins in solution nuclear magnetic resonance (NMR) are treated. We propose a novel technique to calculate the intermolecular multiple-quantum coherences (iMQCs) based on a boson operators approach. The choice of an annihilation and creation operator basis set allows us to produce a general expression of the NMR signal depending on local inhomogeneities of magnetic field. The general expression we derive fits into the well known background of iMQCs signal descriptions [J. Jeener, J. Chem. Phys. 112 (2000) 5091] and turns into the conventional quantum-mechanical Warren formulation [S. Lee, W. Richter, S. Vathyam, W.S. Warren, J. Chem. Phys. 105 (1996) 874] by means of appropriate approximations.