[Zurück]

Y. Wang:
"Hillock formation on CaF₂ surface irradiated by medium energy highly charged xenon ions (Selected oral contribution)";
Vortrag: 26th International Conference on Atomic Collisions in Solids (ICACS-26), Debrecen/Hungary; 17.07.2014.

S
low highly
charged ions (HCI) can induce surface modification at a
nanometric
scale [1]. Concentrating on CaF
2
, El
-
Sai
d et al. [2]
found that
hillocks are only observed
above a charge state of 28+
for xenon ion
s
with
very low kinetic energy (0.004 MeV)
.
Similarly, nanohillocks
have previously also been observed after impact of
individual
swift heavy ions (SHI) on a CaF
2
s
urface above a certain impact energy threshold [
3
].
In order to get a more
complete understanding of intense electronic excitation in
a
broad range of potential and kinetic energies, nano
-
modifications
on CaF
2
surfaces
have been studied using
swift heavy
ions
at
GANIL (Caen) and medium energy highly
charged ions
at IMP
(Lanzhou). With 3 and 5 MeV Xe
q+
projectiles we clearly observe
hillocks at projectile charge
states lower than 26+.
It is
therefore
conclude
d
that the
necessary electronic excitation to ind
uce a
nano
-
hillock can be either deposited in the
form of
electronic energy loss (SHI) or potential energy (slow HCI)
or a combination of
both (medium energy case). In fact
a detailed
analysis
of
our experimental findings
indicate an additive
interaction o
f the two mechanisms of energy deposition,
electronic
energy loss and potential energy [
4
]. Such a
relation suggests that the inelastic thermal
spike model can
be extended to describe surface modification induced by
both SHI and
slow HCI [
5
].