We generalize earlier work [V. G. Stavros, E. Harel, S. R. Leone, J. Chem. Phys. 122 (2005) 064301] by illustrating the plausible role of ion gratings in time-dependent degenerate four-wave mixing (TD-DFWM) experiments in H-2. We postulate that at high laser intensities (10(14)-10(15) W/cm(2)), H-2(+)/H+ ions generate a static ion grating, it's signature manifested in the transformation from homodyne- to hetero dyne-detection of the TD-DFWM signal, depending on laser intensity. The change in signal detection agrees with the calculated intensity for barrier suppression ionization (BSI) in H-2 and the reported onset of saturation for H-2(+) and H+, pointing towards the likely role of ion gratings in intense laser field, FWM experiments. (c) 2007 Elsevier B.V. All rights reserved.