Structural properties of alkali halide surfaces (KBr, KI, and RbI) have beenmodified by low energy Ar+ ion beam bombardment. The morphology developed on the irradiated surfaces was investigated by the atomic-force microscopy (contact mode) under UHV conditions. The results indicate that for the incidence angles between 308 and 408 a periodic ripple morphology is developed with the ripple vector parallel to the beam direction, whereas for the angles larger than 608 the vector is perpendicular to the beam. The average surface roughness and the wavelength of the ion-induced periodic structures were measured as a function of the ion fluence (10(13)-10(18) ions/cm(2)), the beam energy (1-5 keV), and the sample temperature (from 300 K to 600 K). The results are explained in terms of a new atomic-scale model taking into account the fact that ion sputtering of alkali halides in the investigated energy range is dominated by electronic processes rather than ballistic collisions. (C) 2008 Elsevier B. V. All rights reserved.