Role of inhomogeneous widening in radiofrequency coherent superradiation from highly polarized spin systems

We discuss the coherent behavior of a highly polarized, nuclear or electron, spin system for which the magnetic dipole radiation, emitted in the radio-frequency region, has a quadratic dependence on the number of spins. Phenomenological theories are unable to completely predict many of the features of low-temperature spin systems. Computer simulations provide a very effective and accurate method of describing such systems. Our investigation is based on a microscopic model, which makes it possible to accurately analyze the role of dipole interactions and inhomogeneous widening. Inhomogeneous a widening complicates the behavior of the system leading to a longer delay in the appearance of the superradiation pulse and a decrease in its intensity. If the inhomogeneity is large enough, it destroys the coherence in a spin system at times shorter than the characteristic dipole relaxation time.