I. Koponen et M. Hautala, THERMALIZATION OF SPARSE COLLISION CASCADES IN METALS - SIMULTANEOUS RELAXATION OF NONEQUILIBRIUM ELECTRON AND ION DISTRIBUTIONS, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 90(1-4), 1994, pp. 396-400
Thermalization of ion bombardment induced large and sparse cascades in
metals is studied. We introduce a model where nonequilibrium electron
and ion distributions relax simultaneously, and coupling between the
thermal ions and valence electrons allows heat exchange between electr
onic and ionic systems. This model takes into account the competing ti
me scales of the relaxation processes and the heat outdiffusion from t
he cascade zone. Nearly free conduction electron bands are assumed, wh
ich restricts the applicability of the model to simple metals only. It
is shown that in cascades with an extent of about 10 nm or more, a co
nsiderable part of the energy, residing initially in the electronic sy
stem, may reappear in the ionic system in the cascade zone. Ions in ca
scades with radius larger than 20 nm take up nearly all of the energy
available in the cascade zone. Due to this energy transfer, the ionic
system may experience appreciable additional heating in large cascades
.