Porous track cores along wakes of swift Pb ions in LiF

Continuous density decreases of ∼50% within 98 μm long and 3.2 nm wide cylindrical ion damage trails, latent ion tracks, created in a {1 0 0} LiF platelet by 2.31 GeV Pb ions, have been measured by small-angle X-ray scattering. Structural alteration is attributed mainly to radiolytic decomposition of the crystal into Li atoms and fluorine molecules, and subsequent transport and release of the fluorine gas through the low-density tracks. Free volume and Li residues undoubtedly account for the observed enhanced etchability of the track-core region.