The paper presents a study aimed to extract information on individual tracks in nearly monodisperse poly(methyl methacrylate) bombarded with 200 keV He+ ions. The study of the molecular weight distribution of the polymer after low fluence irradiation shows that it is possible to identify the contribution of the individual tracks to the overall distribution, in particular it is shown that the extraction of useful information about the mechanism of scission of the macromolecules inside the ion tracks in the low fluence limit (''single track regime'') is not obtainable by means of a simple data treatment of the experimental molecular weight distribution. Hence, a model simulation of the macromolecular scission has been developed that allows us to obtain the bond scission probability in the energy conditions studied here (200 keV Hei). Comparison with experimental data indicates that only a negligible part of the macromolecules in the tracks undergo more than two scissions per macromolecule and that the most part of the macromolecules undergo only one scission event, in the energy condition used here (200 keV He+). (C) 1997 Elsevier Science B.V.
Individual tracks in ion bombarded poly(methyl methacrylate)
FRAGALA', Maria Elena;LICCIARDELLO, Antonino;
1997-01-01
Abstract
The paper presents a study aimed to extract information on individual tracks in nearly monodisperse poly(methyl methacrylate) bombarded with 200 keV He+ ions. The study of the molecular weight distribution of the polymer after low fluence irradiation shows that it is possible to identify the contribution of the individual tracks to the overall distribution, in particular it is shown that the extraction of useful information about the mechanism of scission of the macromolecules inside the ion tracks in the low fluence limit (''single track regime'') is not obtainable by means of a simple data treatment of the experimental molecular weight distribution. Hence, a model simulation of the macromolecular scission has been developed that allows us to obtain the bond scission probability in the energy conditions studied here (200 keV Hei). Comparison with experimental data indicates that only a negligible part of the macromolecules in the tracks undergo more than two scissions per macromolecule and that the most part of the macromolecules undergo only one scission event, in the energy condition used here (200 keV He+). (C) 1997 Elsevier Science B.V.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
