Interatomic distance dependence of resonant energy-transfer phenomena.

It is well known that interatomic or intermolecular interactions driven by two-center electronic dipole-dipole correlations fall off rapidly with the inter-site distance. We show, however, that the effective strength of interatomic reaction channels, which are triggered by a resonant field, can exhibit a nonmonotonous distance dependence, being strongly reduced when the atoms come closer. This surprising result is demonstrated by considering resonant two-center photoionization as an example. Our findings are supported by available experimental data.