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

MeV N+ and N-2(+) ions were used to induce Li+ desorption from LiF. The con tributions due to elastic atomic collisions;and electronic excitation proce sses 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 foun d only for the electronic process. The maximum sputtering yield was observe d in a projectile velocity range where the projectile electronic energy los s still increases. These results are simultaneously explained using the rad ial distribution of the deposited energy rather than the electronic energy loss.