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C. Dufour, V. Khomorenkov, Y. Wang, Z. Wang, F. Aumayr, M. Toulemonde:
"An attempt to apply the inelastic thermal spike model to surface modifications of CaF₂ induced by highly charged ions: comparison to swift heavy ions effects and extension to some others material";
Journal of Physics: Condensed Matter, 29 (2017), 0950011 - 09500116.

Surface damage appears on materials irradiated by highly charged ions (HCI). Since a direct
link has been found between surface damage created by HCI with the one created by swift
heavy ions (SHI), the inelastic thermal spike model (i-TS model) developed to explain track
creation resulting from the electron excitation induced by SHI can also be applied to describe
the response of materials under HCI which transfers its potential energy to electrons of the
target. An experimental description of the appearance of the hillock-like nanoscale protrusions
induced by SHI at the surface of CaF2 is presented in comparison with track formation in bulk
which shows that the only parameter on which we can be confident is the electronic energy
loss threshold. Track size and electronic energy loss threshold resulting from SHI irradiation
of CaF2 is described by the i-TS model in a 2D geometry. Based on this description the i-TS
model is extended to three dimensions to describe the potential threshold of appearance of
protrusions by HCI in CaF2 and to other crystalline materials (LiF, crystalline SiO2, mica,
LiNbO3, SrTiO3, ZnO, TiO2, HOPG). The strength of the electron-phonon coupling and the
depth in which the potential energy is deposited near the surface combined with the energy
necessary to melt the material defines the classification of the material sensitivity. As done for
SHI, the band gap of the material may play an important role in the determination of the depth
in which the potential energy is deposited. Moreover larger is the initial potential energy and
larger is the depth in which it is deposited.

transient thermal process, highly charged ions, swift heavy ions, ion tracks, CaF2, SiO2, SrTiO3, TiO2