99-27E

Generalized collective mode approach is applied for the study of transverse dynamics in binary mixtures. The scheme is based on simultaneous treatment of conserved total mass current and mutual mass-concentration current, as well as their time derivatives. A condition of existence of optic-like transverse modes in a binary system is derived. It is shown, that high mutual diffusion and tendency to demixing prevent the emergence of transverse optic-like modes. The optic-like excitations are found in a Lennard-Jones KrAr fluid, liquid metallic alloys Mg$_{70}$Zn$_{30}$ and Li$_{4}$Pb, while in `fast-sound' dense gas mixture He$_{75}$Ar$_{25}$ they do not appear for small wavenumbers.