  We observe and investigate, both experimentally and theoretically,
electromagnetically-induced transparency experienced by evanescent fields
arising due to total internal reflection from an interface of glass and hot
rubidium vapor. This phenomenon manifests itself as a non-Lorentzian peak in
the reflectivity spectrum, which features a sharp cusp with a sub-natural width
of about 1 MHz. The width of the peak is independent of the thickness of the
interaction region, which indicates that the main source of decoherence is
likely due to collisions with the cell walls rather than diffusion of atoms.
With the inclusion of a coherence-preserving wall coating, this system could be
used as an ultra-compact frequency reference.
