We present scanning force microscope images of craterlike defects induced by individual 78.2-MeV ${}_{}{}^{127}{}_{}{}^{}\mathrm{I}$ ions incident on organic single-crystal L-valine surfaces. For grazing incidence ions, the craters are elongated along the ion azimuth of incidence and display a raised tail in the surface above the ion track. This permanent plastic deformation of the surface indicates that a hydrodynamic pressure-pulse phenomenon occurs in response to the electronically deposited energy.

• Received 21 July 1993

DOI:https://doi.org/10.1103/PhysRevB.49.625