Product translational energy distributions have been used in previous studies as a diagnostic of surface reaction enhancement mechanisms under ion bombardment. Haring and co‐workers [R. A. Haring, A. Haring, F. W. Saris, and A. E. de Vries, Appl. Phys. Lett.41, 174 (1982)] have taken anE−2dependence for SiFxspecies desorbing during ion‐enhanced etching of silicon as evidence for the importance of physical sputtering. In this work, the translational energy distribution of SiF4desorbing from the surface of silicon during spontaneous etching by XeF2has been obtained from modulated beam measurements. The distribution deviates markedly from a thermal distribution at the surface temperature and exhibits anE−2dependence at high energy. Observation of this energy dependence both with and without ions suggests that translational energy distributions may not provide a unique signature for chemical and physical sputtering.