Excitation process simulation for atoms leaving a metal surface

Recently, experimental data about the dependences of secondary atom excitation probability on atom velocity were obtained. In the present work an attempt is made to give a theoretical explanation. We used a model with the Anderson-type Hamiltonian, where all possible resonant and non-resonant single-electron processes, taking part in "metal-emitted multi-level particle" system, are taken into account. Calculations which are carried out in the frame of the proposed model are found to be in good quantitative agreement with the experimental data and explain facts such as: (1) the high efficiency of the electron-exchange mechanism in secondary atom excitation, (2) the relatively slow dependence of the probability of excitation of secondary atoms on their velocity, (3) the non-trivial characteristic type of such dependence for the secondary atom excitation and ionization probabilities. (C) 2002 Elsevier Science Ltd. All rights reserved.