Secondary ion emission from Cu(100) surfaces with atomicadsorbates (N, O, Cl, S and Br)

摘要

Several targets that consist of atomic species X (X = N, O, Cl, S, Br) adsorbed at hollow sites on the Cu( 100) surface have been examined with low-fluence secondary ion mass spectrometry (SIMS). The positive and negative secondary ion (SI) abundance distributions, which show a range of characteristics, have been discussed with the aid of thermochemical data derived from ab initio calculations. In positive SIMS, CuX~+ is never observed, while the only heteronuclear (mixed-atom) SI that is observed for all five systems is Cu_2X~+. In negative SIMS, the dominant heteronuclear species for all systems is CuX_2, except for N/ Cu(l 00), which produces no CuN_k, ions. Cu~ emission is observed only for O/Cu(l 00). By analogy with results from laser ablation studies of O/Cu targets, it is conjectured that Cu~- is a daughter product of the gas-phase dissociation of polyatomic Cu-0 anion clusters.