Magnetic dipole-dipole transition for scintillation quenching

Abstract

A magnetic dipole-dipole interaction is proposed as a scintillation quenching mechanism. The interaction rate follows $R^{-6}$ as the electric dipole-dipole interaction in F$\mathrm{\ddot{o}}$ster resonance energy transfer theory. The proposed mechanism causes a long-range resonance energy transfer, and the resonance condition is that the spins of donor and acceptor electrons both flip, and the energy level differences are the same. The new mechanism is distinct to the known spin-orbit coupling induced intersystem crossing, and it can enhance the overall intersystem crossing rate. When oxygen or organic molecules including heavy elements are dissolved in a liquid scintillator, these requirements are possible to be satisfied. The proposal in the paper adds a new approach for scintillation quenching in liquid scintillators.