Scanning force microscopy of ion-irradiated organic single crystals of benzoyl glycine

Single crystals of the amino acid benzoyl glycine (hippuric acid) are irrad iated normal to the as-grown surface by highly charged Bi ions with a kinet ic energy of 2.38 GeV and a fluence of 1 x 10(10) ions/cm(2). The projectil es create circular craters with a mean diameter of 40 (10) nm on the surfac e of the crystal as observed by scanning force microscopy (SFM). The mean d epth amounts to 4(1)nm, this value bring considered as a lower limit due to the finite radius of curvature of the force cantilever tip. Thus, on the a verage, each single-ion projectile seems to eject about 10(4) molecules. On the surface of non-irradiated crystals, SFM reveals terraces of a few mono layers in height. In water, it was possible to visualize the lattice period icity. Terraces were also observed on the irradiated crystal surface in the presence of the craters, indicating that the crystal is still intact at th e given dose.