Thermal spikes and sputtering yields

Collision Cascades, Ionization, Spikes And Energy Transfer

The collisions of an individual energetic ion in a solid set atoms of the solid in motion and excite electronic states. The moving atoms collide with others to form a collision cascade and the electronic excitation also forms a branched trail around the track of the ion. If the densities of the energy deposition in either of these modes is high the result is called a “spike”. The low density regimes of collision and ionization cascades and evidence for the transition to non-linear high density spikes are summarized. The understanding of the latter is still quite incomplete as is also understanding of the transfer of energy between the kinetic and the electronic modes, particularly at high energy densities.

Jetlike component in sputtering of LiF induced by swift heavy ions

Angular distributions of sputtered atoms from SiO2 and LiF single crystals were measured under the irradiation of 1 MeV/u swift heavy ions. In contrast to the almost isotropic distribution of SiO2, an additional jetlike component was observed for LiF. The total sputtering yield of SiO2 ( approximately 10(2) atoms/ion) can be reproduced by an extended inelastic thermal spike model, whereas the huge yield of LiF ( approximately 10(4) atoms/ion) needs a substantial decrease of the sublimation energy to be described by the model.