  A method is proposed for producing atom gratings having period $\lambda /4$
and $\lambda /8$ using optical fields having wavelength $\lambda $.
Counterpropagating optical fields drive Raman transitions between ground state
sublevels. The Raman fields can be described by an effective two photon field
having wave vector 2 k, where k is the propagation vector of one of the fields.
By combining this Raman field with {\em another} Raman field having propagation
vector -2 k, one, in effect, creates a standing wave Raman field
\label{91}%which whose ``intensity'' varies as $\cos (4 k\cdot r).$ When atoms
move through this standing wave field, atom gratings having period $\lambda /4$
are produced, with the added possibility that the total ground state population
in a given ground state manifold can have $\lambda /8$ periodicity. The
conditions required to produce such gratings are derived. Moreover, it is shown
that even higher order gratings having periodicity smaller than $\lambda /8$
can be produced using a multicolor field geometry involving three (two-photon)
Raman fields. Although most calculations are carried out in the Raman-Nath
approximation, the use of Raman fields to create reduced period optical
lattices is also discussed.
