Reduction of the natural width of atomic levels in nanostructured systems

It is shown that given the certain distances between atoms, in atom cluster occurs the effect of narrowing of atom level natural width due to retarded interaction in the field of outer radiation. Interatomic interaction leads to both the displacement of atom levels and the occurrence of an inflection point separating the areas of negative and positive dispersion of atomic cluster effective polarizability. It is also shown that the local field, under conditions of atom level natural width narrowing, significantly exceed the outer field, which leads to strengthening of cluster's optical field in the wave zone beyond the cluster. If one changes some internal conditions in the cluster, the cluster's dipole radiation may flicker. The discovered effect of narrowing takes place in the field of low-intensity outer radiation without changing the inverse of atomic quantum transitions.