Interaction potential for neutral mesoscopic particles under illumination

We discuss the interaction potential induced by an external electromagnetic field in particle assemblies. We show that when electromagnetic resonances are excited in the assembly, corresponding potential minima are expected in the interaction potential. These minima give rise to bound states with frequency-dependent spatial parameters. The strength of the interaction scales with laser power and under strong illumination the agglomeration rate may be increased in dilute systems, while phase transitions may be induced in bound systems capable of more than one collective electromagnetic resonance.