Short-time vibrational dynamics of acetylene versus its isotopic variants

The short-time intramolecular dynamics of highly vibrationally excited HCCD and DCCD, as determined by classical trajectories, have qualitative features distinct from HCCH and from one another. The possible differences are also considered from the point of view of the symmetries of the normal modes. The short-time evolution will be reflected in the coarse-grained frequency spectrum and could be detectable via stimulation emission pumping.