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Title: Vicinage effects in ion-cluster collisions with condensed matter and with single atoms

Journal Article · · Phys. Rev. A; (United States)

The excitation of electronic transitions in matter by a group of swift ions traveling close together and at nearly the same velocity may depend on the spatial configuration of ions making up the cluster. We have studied theoretically the effect of configuration on the interactions of clusters with an electron gas and in collisions with single atoms (vicinage effect). The latter case is explored using a classical harmonic-oscillator model and with quantum-mechanical perturbation theory. We discuss similarities between the vicinage function for energy loss of a swift cluster in the electron gas and that for the same cluster colliding with a system of noninteracting atoms at condensed-matter density. The aligning effect of the wake potential on the trailing ion of a dicluster penetrating a solid target, as first observed by Gemmell et al., is not expected to occur in cluster collision with single atoms, and does not occur in collision with gases at ordinary pressures. Aligning forces comparable with those in solids require target densities of the same order of magnitude as those occurring in condensed matter. The data of Lurio, Anderson, and Feldman taken in a search for vicinage effects in inner-shell excitation are discussed. The effect of wake fluctuations on cluster energy loss is shown to be negligible under ordinary conditions. We evaluate the effect of residual molecular ionic structure on cluster energy loss.

Research Organization:
Department of Physics, North Texas State University, Denton, Texas 76203
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
5197789
Journal Information:
Phys. Rev. A; (United States), Vol. 25:4
Country of Publication:
United States
Language:
English