Cluster and velocity effects on yields and kinetic energy distributions of Li+ desorbed from LiF

MeV N+ and N-2(+) ions were used to induce Li+ desorption from LiF. The contributions due to elastic atomic collisions;and electronic excitation processes to the sputtering yield could he unambiguously separated. In the case of N-2(+) ions, a Li+ yield enhancement, i.e., Y(N-2(+)) > 2Y(N+), was found only for the electronic process. The maximum sputtering yield was observed in a projectile velocity range where the projectile electronic energy loss still increases. These results are simultaneously explained using the radial distribution of the deposited energy rather than the electronic energy loss.