Charge-induced wettability modification

Electric charges deposited on a liquid droplet, located on a solid surface, strengthen the wetting effect. Here, the authors report on the opposite phenomenon-a decrease of wettability induced by a low-energy electron irradiation of solids. They provide evidence that the electron-induced surface charge decreases solid/liquid and solid/vapor interfacial energies when reduction of the latter is always higher. This explains the observed dependence of the droplet shape on the incident electron charge and energy, as well as on a liquid origin. This phenomenon is reversible when the charged material is subjected to ultraviolet illumination, which restores its initial state. (c) 2007 American Institute of Physics.