  We show that (near-)zero energy proton emission from H$_2^+$ in strong
two-color and broadband laser fields is dominated by a stimulated Raman
scattering process taking place on the electronic ground state. It is
furthermore shown that in the (near-)zero energy region the asymmetry in proton
ejection induced by asymmetric laser fields is due to the interplay of several
processes, rather than only pathway interferences, with vibrational trapping
(or bond-hardening) taking a key role.
