کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10674899 1010552 2005 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Carbonization of polyimide by swift heavy ion irradiations: Effects of stopping power and velocity
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سطوح، پوشش‌ها و فیلم‌ها
پیش نمایش صفحه اول مقاله
Carbonization of polyimide by swift heavy ion irradiations: Effects of stopping power and velocity
چکیده انگلیسی
We have studied the carbonization of polyimide Kapton-H (pyromellitic dianhydride-oxydialinine, PMDA-ODA) thin films under heavy ion irradiations in the electronic slowing down regime. Irradiations were performed with 650-MeV Ni, 843-MeV Xe, 2.6-GeV Xe, 1.1-GeV Ta, and 707-MeV Pb ions that were transmitted through the polymer films with the electronic stopping power ranging between 3.5 and 17 keV nm−1. Room-temperature ac/dc electrical conductivity measurements, together with ESR, UV-visible optical absorption, and micro-Raman spectroscopy were used to characterize the irradiated films. These new data are compared to our previous results obtained with heavy ion irradiations in the 1-MeV uma−1 energy range. At the largest fluences near 1013 cm−2 the resulting carbonaceous material is found to be 8-9 orders of magnitude less conducting than with the slower ions. Such large dc-conductivity deviations are confirmed by the spin-lattice relaxation times deduced from the ESR line saturation measurements that are two orders of magnitude longer with the swift ions than with the slower ions. The evolution of the Raman spectra also shows that the appearance of a conjugated sp2-bonded structure is delayed with respect to the slow ion case, and is probably incomplete in the observed fluence range. The yield of paramagnetic centers is found to decrease when the ion energy increases. This is interpreted by an ion-velocity effect on damage due to a dilution of the deposited energy in the ion tracks. We think that this also induces a smaller sp2 cluster density impeding charge transport in the carbonaceous material.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms - Volume 234, Issue 4, July 2005, Pages 458-466
نویسندگان
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