  Plasmonic structures are known to support the modes with subwavelength
volumes in which the field matter interactions are greatly enhanced. Coupling
between the molecular excitations and plasmons leading to formation of
plexcitons has been investigated for a number of organic molecules. However,
plasmon-exciton coupling in metal semiconductor structures have not experienced
the same degree of attention. In this work we show that the very strong
coupling regime in which the Rabi energy exceeds the exciton binding energy is
attainable in semiconductor cladded plasmonic nanoparticles and leads to
formation of Wannier Exciton Plasmon Polariton (WEPP) that is bound to the
metal nanoparticle and characterized by dramatically smaller (by factor of few)
excitonic radius and correspondingly higher ionization energy. This higher
ionization energy exceeding approaching 100meV for the CdS/Ag structures may
make room temperature Bose Einstein condensation and polariton lasing in
plasmonic/semiconductor structures possible
