  We describe the experimental verification of lattice resonances in
two-dimensional photonic crystals constructed from an array of gaseous plasma
columns. Enhancements are seen in the extinction of normal incidence transverse
electric electromagnetic waves when the localized surface plasmon modes of the
plasma columns are shifted into the vicinity of the photonic crystal Bragg
resonances. Simulations and experiments are in reasonable agreement and confirm
the appearance of a Fano-like profile with deep and broad extinction bands. The
broadening of the spectra as surface plasmon modes come into coincidence with
Bragg gaps suggest that the Bragg fields couple strongly into the radiating Mie
dipoles to drive enhanced damping of the photonic crystal resonance.
