Secondary electron, ion and photon emission during ion beam irradiation of polymer and condensed gas films (original) (raw)
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Ion beam effects in polymer films: Structure evolution of the implanted layer
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1997
Thin films of polyethylene, polyamide-6 and cellulose implanted with 100 keV B+, Nf and Sb+ ions to the fluences of 10'3-10'7 cmv2 were investigated using RBS and NDP techniques as well as IR, UV-visible and EPR spectroscopies. The peculiarities of the depth distribution of implanted species and the origin of the processes responsible for modification of the structural, optical and paramagnetic properties of polymers are discussed with consideration for two major reactions occurring in the implanted layer: (i) oxidation of the radiation-damaged polymer that predominates at moderate doses; (ii) clusterization of radiation defects with the formation of carbon-enriched domains ("drops") which can overlap at high ion fluences yielding the network of conjugated carbon structures.
High energy ion beam irradiation of polymers for electronic applications
Ion irradiation of polymers offers a number of interesting possibilities for applications. In the case of latent tracks, radiochemical changes, phase transitions, alterations of the intrinsic free volume, or radiation induced defects can be exploited -the latter ones to trap mobile impurities. These approaches are useful to form, e.g. new types of sensors.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1991
The keV-MeV ion irradiation of polymers produces deep changes in their physical and chemical properties associated with the breaking and rearrangement of original bonds. The modification of chain structure occurs within a well defined ion fluence range which depends on the ion linear energy transfer as well as on the target parameters. At low ion fluences (≈1014 ions/cm2) crosslinks between chains and chain-scissions are detected with a chemical yield in the range 0.05–0.3, depending on the ion mass. With increasing ion fluence (1015 ions/cm 2) the original polymer structure is heavily modified and the irradiated films exhibit properties close to those of hydrogenated amorphous carbon. At very high fluences (≈1016 ions/cm 2) graphitization of the material occurs.
XPS study of ion beam irradiation effects in polyimide layers
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1989
Thin polyimide films deposited on silicon or metal covered glass-ceramic substrates were exposed to ion bombardment at different fluences ranging from 1 X lo'* to 1.5 X lOi6 cm-*. The XPS technique was used to study the polymer stoichiometry of the near surface layers ( -75 A) before and after the bombardment.
Structural modification of polymer films by ion irradiation
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1992
The atomic and electronic structure of polymer films undergoes deep modifications during high energy (keV-MeV) ion irradiation, from molecular solid to amorphous material. At low energy density (1022–1024) typical effects include chain scissions, crosslinks, molecular emission and double bonds formation. In hydrocarbon polymer (polystyrene, polyethylene) the main effect of irradiation is the formation of new bonds as detected by molecular weight distribution, solubility and optical measurements. Moreover the concentration of trigonal carbon (sp2) in the polymer changes with ion fluence (1011–1014) and stabilizes to a value of 20% independently on the initial chemical structure of the irradiated sample. Photoemission spectroscopy shows an evolution of valence band states from localized to extended states. At high energy density (1024–1026) the irradiated polymer continues to evolve showing spectroscopic characteristics close to those of hydrogenated amorphous carbon. Trigonal carbon concentration changes with ion fluence (1014–1016) reaching the steady state value of 60% and the hydrogen concentration decreases to 20%. Moreover the values of the optical gap (2.5–0.5 eV) suggest the presence of medium range order in the obtained hydrogenated amorphous carbon. These values are consistent with the formation of graphitic clusters, whose size goes from 5 Å to 20 Å by changing the ion fluence (or energy density).
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2002
In this work the real time evolution of luminescence properties of ion-irradiated polymer thin films was studied by means of ion beam induced luminescence (IBIL) measurements. The plastic scintillator NE102, a fluorinated polyimide and PMMA were irradiated by H þ (1.85 MeV), He þ (2.2 MeV) and N þ (1.2 MeV). The optical properties after irradiation were analysed with UV-Visible absorption, fluorescence spectroscopy and Fourier transform infrared spectroscopy (FT-IR), in order to correlate the IBIL measurements to the evolution of the optical and chemical properties of the matrix. Ó
Ion irradiation induced chemical changes of polymers used for optical applications
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1997
Polymers are a class of materials widely used in different fields of applications. In the field of optical telecommunication, polymers are discussed as a new class of materials for the fabrication of passive optical devices. Ion irradiation is a promising method to generate structures with a modified index of refraction, which is necessary for the guidance of light with different wavelengths in an optical device. The behaviour of different polymers which fulfil the requirements of high transparency has been studied during and after ion irradiation. Mass spectroscopy measurements of the reaction products outgassing during ion irradiation were performed as well as infrared (IR) measurements after irradiation. Ion induced chemical changes will be discussed in relation to modified macroscopic properties such as the index of refraction.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
The influence of the molecular structure on the secondary ion production is studied for three saturated aliphatic polymers (low-density polyethylene, polypropylene and polyisobutylene) bombarded with low energy ions. These polymers differ only by the presence and nature of the pendant group. The intensities of the most characteristic secondary molecular ions are followed as a function of the primary ion dose in the (1012 ions/cm2-1014 ions/cm*) range for two primary ion bombardment conditions (4 keV XeC and 15 keV Ga+). The results show that there is a direct relationship between the polymer degradation and the emission of molecular fragments. No truly "static" conditions are found, rather, the polymer surface undergoes a continuous transformation under ion beam bombardment. The most spectacular effect is its dehydrogenation. By rationalizing the competition between the two related processes, surface degradation and molecular ion production, a kinetic model is proposed in order to explain the behavior of molecular fragments belonging to the C8 cluster.
Claquage diélectrique lors d'irradiation de films minces de polymères
Éditions Universitaires Européennes, 2015
Le but de ce travail est de mieux comprendre les modifications des propriétés physico-chimiques induites à la surface d’échantillons de films minces de polymères isolants soumis au profilage ionique en spectrométrie de masse d’ions secondaires (SIMS). En début d’opération, les signaux ioniques provenant de la surface subissent une variation transitoire avant d’atteindre un régime stationnaire. Cela signifie que l’information liée aux premières couches de la surface est compromise. La phase transitoire du signal SIMS n’a jamais été considérée dans les analyses, alors que les modifications structurales et chimiques apportées aux échantillons organiques, durant cette phase transitoire, influent sûrement sur les informations obtenues pendant l’analyse SIMS dans le régime stationnaire. L’étude des distributions énergétiques des ions secondaires, prouve que l’accumulation de la charge électrique à la surface des échantillons, provoque le claquage diélectrique des films minces de polymères organiques isolants irradiés. Les résultats obtenus par la spectroscopie de photoélectrons X montrent la création d’une phase conductrice, qui permet la neutralisation de la charge électrique accumulée.