  Isobaric charge-exchange reactions induced by beams of 112Sn have been
investigated at the GSI facilities using the fragment separator FRS. The
high-resolving power of this spectrometer makes it possible to obtain the
isobaric charge-exchange cross sections with an accuracy of 3% and to separate
quasi-elastic and inelastic contributions in the missing-energy spectra, in
which the inelastic component is associated to the in-medium excitation of
baryonic resonances such as the $\Delta$ resonance. We report on the results
obtained for the (p,n) and (n,p) channels excited by using different targets
that cover a large range in neutron excess.
