Latent (sub-surface) tracks in mica studied by tapping mode scanning force microscopy

This short communication presents information on the structure of latent (i.e subsurface) tracks in muscovite mica due to single 78.2 MeV I-127 ions incident at an angle of 67 degrees with respect to the surface normal. The latent tracks have been studied for the first time using tapping mode scanning force microscopy. Images of an underlying mica surface, exposed by cleaving after ion bombardment, displayed hillocks accompanied by raised tails, These features were significantly lower in height compared to similar features observed on the originally outermost mica surface. The inner back surface of the mica sheet cleaved away also displayed shallow hillocks with raised tails, but on that surface, the tails stretched in the opposite direction to those observed on the originally outermost mica surface. On both surfaces exposed by cleaving, the tail is located in close proximity to the latent ion track, showing a symmetry of expansion along the track. The present results provide more evidence for a permanent expansion occurring around each ion track, as described qualitatively by theoretical models.