Surface defect formation on gypsum surfaces due to grazing incidence 78.2 MeV 127I ions: A comparative study employing tapping-mode scanning force microscopy and shadow-replica electron microscopy

Abstract

We have performed, for the first time, comparative studies of surface tracks employing both tapping-mode scanning force microscopy (TM-SFM) and shadow-replica electron microscopy (SR-EM). The surface tracks, with dimensions of the order of 10 to 100 nm, were induced on gypsum by 78.2 MeV 127I ions impacting at surface-grazing angles of incidence. Using TM-SFM, finite probe-tip radius of curvature limited the available spatial resolution, and under some conditions, apparent deformation of the surface defects was observed, indicating that TM-SFM can be sensitive to surface properties besides topography. Rim-to-rim crater widths (perpendicular to the ion incidence azimuth) and overall lengths (parallel to the ion incidence azimuth) were measured equivalently by TM-SFM and SR-EM. However, the defect heights were somewhat overestimated by TM-SFM relative to SR-EM. Each surface track caused by an incident swift, heavy atomic ion is considered to represent the material response to an explosive vaporization process which cracks open the surface.