  We study the plasmonic energy transfer from a locally excited nanoparticle
(LE-NP) to a linear array of small NPs and we obtain the parametric dependence
of the response function. An analytical expression allows us to distinguish the
extended resonant states and the localized ones, as well as an elusive regime
of virtual states. This last appears when the resonance width collapses and
before it becomes a localized state. Contrary to common wisdom, the highest
excitation transfer does not occur when the system has a well defined extended
resonant state but just at the virtual-localized transition, where the main
plasmonic modes have eigenfrequencies at the passband edge. The slow group
velocity at this critical frequency enables the excitation buffering and hence
favors a strong signal inside the chain. A similar situation should appear in
many other physical systems. The extreme sensitivity of this transition to the
waveguide and LE-NP parameters provides new tools for plasmonics.
