We investigate theoretically a trap formed by two laser evanescent wav
es propagating at the surface of a dielectric prism, which confine the
atoms in a Morse potential along the direction perpendicular to the p
rism. We consider a loading process based on the Sisyphus effect, in w
hich a single spontaneous Raman transition is involved. We show that i
t is possible to achieve in this way an efficient loading of the groun
d state of the Morse potential, and to get thus a quasi-bi-dimensional
atomic gas at the surface of the dielectric.