Polyethylene (PE) was irradiated with 63 keV Ar+ and 156 keV Xe+ ions (R-P
= 100 nm for both ions) to the fluences from 1 x 10(13) to 3 x 10(15) cm(-2
). Degradation processes in the PE surface layer, modified by the ion irrad
iation, were characterized by measuring depth profiles of residual hydrogen
and incorporated oxygen (RBS/ERD techniques), free radical concentration (
EPR) and conjugated double bond concentration (UV-VIS). Dehydrogenation due
to release of a part of volatile degradation products was observed. Intera
ctions among free radicals, produced along the ion path, result in a creati
on of new, conjugated double bonds. Some of free radicals react with oxygen
coming from ambient atmosphere in the ion implanter and in this way, oxidi
zed structures are produced. Dehydrogenation of PE chains and degradation o
f oxidized structures, appear to be related to the energy locally deposited
via ion electronic energy loss. (C) 2000 Elsevier Science Ltd. All rights
reserved.