Ion Beam Irradiation Ion Beam Irradiation Effects on Effects on Polymers Polymers Mircea Chipara Mircea Chipara Now at: Now at: The University of The University of Texas Texas Pan American Pan American Department of Department of Physics and Geology, Physics and Geology, Edinburg, TX 78541 Edinburg, TX 78541
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Ion Beam Irradiation Ion Beam Irradiation Effects on Polymers Effects on Polymers
Mircea ChiparaMircea ChiparaNow at:Now at:
The University of TexasThe University of TexasPan AmericanPan American
Department of Physics and Department of Physics and Geology, Edinburg, TX Geology, Edinburg, TX
7854178541
1.1. Excitations of individual atoms and molecules.Excitations of individual atoms and molecules.2.2. Excitations of several atoms and molecule, leading to Excitations of several atoms and molecule, leading to
collective motions inside the target.collective motions inside the target.3.3. Phonons generation and sample heating. Phonons generation and sample heating. 4.4. Breaking of chemical bonds. Breaking of chemical bonds. 5.5. Ionizations, bond scissions, formation or radicals and Ionizations, bond scissions, formation or radicals and
radical ions. radical ions. 6.6. Atoms sputtering from surface and atom Atoms sputtering from surface and atom
displacements (point defects) within the bulk.displacements (point defects) within the bulk.7.7. Emission of electromagnetic radiation from the Emission of electromagnetic radiation from the
irradiated samples during ion beam bombardmentirradiated samples during ion beam bombardment8.8. The recombination of free radicals (crosslinkingThe recombination of free radicals (crosslinking reactions).reactions).
7.7.
Ion Beam Irradiation Effects Ion Beam Irradiation Effects in Polymersin Polymers
Free radicals generation Free radicals generation in ion beam irradiated polymersin ion beam irradiated polymers
A stack consisting of 18 polycarbonate (MAKROFOL) A stack consisting of 18 polycarbonate (MAKROFOL) layers, each of 8 layers, each of 8 m thickness, with a diameter of 5 cm, m thickness, with a diameter of 5 cm, has been irradiated with Uranium ions accelerated up has been irradiated with Uranium ions accelerated up
to about 10 MeV/nucleon, at “Gesellschaft fur to about 10 MeV/nucleon, at “Gesellschaft fur Schwerionenforschung”, Germany. Schwerionenforschung”, Germany.
The flux of incident ions was about 10The flux of incident ions was about 1088 ions/cm ions/cm22s s and the fluency 10and the fluency 1010 10 ions/cmions/cm22. .
The samples were analyzed by ESR, UV-VIS, The samples were analyzed by ESR, UV-VIS, and luminescence spectroscopy. and luminescence spectroscopy.
Experimental MethodsExperimental Methods
PC+URANIUM IONS
ESR spectrum ESR spectrum shape, position shape, position and tempera-and tempera-ture dependen-ture dependen-ce support for ce support for
the same the same mechanism for mechanism for
ion beam ion beam bombarded bombarded and gamma/ and gamma/
electron electron irradiated PCirradiated PCRadical RRadical R11 is converted into R is converted into R22. above . above
The glass transition temperature, TThe glass transition temperature, TGG..
Gamma irradiatedGamma irradiated
The dependence of ESR line parameters (line intensity The dependence of ESR line parameters (line intensity I and peak to peak line width HI and peak to peak line width HPP PP
on the penetration depthon the penetration depth
The dependence of free radicals concentration The dependence of free radicals concentration on the linear energy transferon the linear energy transfer
UV-VIS spectra of ion beam irradiated PCUV-VIS spectra of ion beam irradiated PC
Ion beam irradiation effect on the energy gap Ion beam irradiation effect on the energy gap of PC- as estimated from UV-VIS spectraof PC- as estimated from UV-VIS spectra
The luminescence spectrum of ion beam bombarded PC
The dependence of the ESR line intensity, luminescence The dependence of the ESR line intensity, luminescence line intensity, energy gap and deposited dose on the line intensity, energy gap and deposited dose on the
penetration depth for the U irradiated PC stack.penetration depth for the U irradiated PC stack.
CONCLUSIONSCONCLUSIONS Polymer chain scission mechanisms implies the generation of free radicals, while the crosslinking can be associated to the free radical decay.ESR is an efficient tool in the study of free radical. Spectroscopic investigations (ESR, VUV, and luminescence) revealed that for ion beam irradiated polycarbonate films the local heating is relatively modest. At least 75% of the latent track is not heated above the melting temperature. ESR data shows that the free radicals are coupled by extreme exchange interactions in clusters along the incident particle track, that the exchange interactions are anisotropic. The linear dependence of the free radical generation on the linear energy transfer is demonstrated.
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