Dynamical instability of thin liquid films between conducting media

It is shown that thin dielectric liquid films between electrically conducting media are dynamically unstable if the electronic work functions of the conductors are different. As a consequence, they are expected to dewet by a spinodal dewetting scenario, i.e., via amplification of surface waves with mode selection. The wave number of the fastest growing mode is discussed as a function of the strength of the electric and dispersive forces. In contrast to what seems to be widely believed, it turns out that electric forces dominate over dispersive forces in most experimental situations of the rather general type studied here.