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V Encuentro Sud Americano de Colisiones Inelásticas en la Materia
Influence of light-ion irradiation on the ion track etching of polycarbonate
R.S. Thomaz 1 , C. T de Souza 2 , and R. M. Papaléo 1
1 Faculty of Physics, Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
2 Institute of Physics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
claudia.telles@ufrgs.br
In this work, we report on the effect of
light-ion irradiation on the pore size distribution
of etched tracks produced by medium
energy heavy ions in polycarbonate. Polycarbonate
foils (Makrofol KG, Bayer, Germany),
about 12 µm thick, were treated with 2 MeV
H + ions of different fluences (1x10 13 to
5x10 14 ions/cm 2 ) either before or after irradiation
with a 18 MeV Au 7+ beam (at a fluence
around 5x10 8 ions/cm 2 ). The heavy ion
irradiation was used to produce the latent
tracks in the foils and the proton beam acted
as a perturbation to the defect distribution.
The sequence of irradiations was performed
at a 3 MV HVEE Tandetron accelerator at
room temperature and without breaking the
vacuum. The irradiated foils were etched
with 6 M NaOH solution at 60 ±1 ºC for 1 to
3 minutes and the etched surfaces analyzed
by scanning electron microscopy. Characterization
of the chemical damage and molecular
weight distribution of the foils was performed
by FTIR spectroscopy, gel permeation
chromatography (GPC) and contact angle
measurements.
The microscopy results showed that the
proton irradiation causes a decrease in the
mean etched pore size as compared to samples
bombarded only with the Au ions
(Fig.1). The reduction effect is greater at H +
fluences around 2 to 5 x10 13 cm -2 , while at
higher H + fluences the pore size start to grow
again, as shown in Figure 2.
Figure 1. SEM images of
etched ion tracks on PC
foils bombarded with different
2 MeV H + fluences.
The samples were first
bombarded by the H + beam
and subsequently irradiated
with the 18 MeV Au
beam to produce the etchable
tracks. (a) control
sample (Au beam only); (b)
=5x10 12 cm -2 ; (c)=
2x10 13 cm -2 ;d=5x10 13
cm -2 ; (e) =2x10 14 cm -2 .
34 Valparaíso, Chile