  IIn this paper we demonstrate a new scheme for Raman transitions which
realize a symmetric momentum-space splitting of $4 \hbar k$, deflecting the
atomic wave-packets into the same internal state. Combining the advantages of
Raman and Bragg diffraction, we achieve a three pulse state labelled
interferometer, intrinsically insensitive to the main systematics and
applicable to all kind of atomic sources. This splitting scheme can be extended
to $4N \hbar k$ momentum transfer by a multipulse sequence and is implemented
on a $8 \hbar k$ interferometer. We demonstrate the area enhancement by
measuring inertial forces.
