  The spatial confinement and the propagation length of surface waves in a
single-layer two-dimensional atomic crystal are analysed in term of its surface
susceptibility and its surface conductivity. Based on the values of these
macroscopic parameters, extracted from experimental observations, it is
confirmed that graphene supports a transverse magnetic non-radiating surface
mode in the ultraviolet spectral region while a single-layer hexagonal
Boron-Nitride is predicted to support a transverse electric non-radiating
surface mode in the visible spectrum. This last mode, at a vacuum wavelength of
633 nm, has a spatial confinement of 15 microns and an intensity-propagation
distance greater than 2 cm.
