Pulsed UV laser-induced modifications in optical and structural characteristics of alpha-irradiated PM-355 SSNTD.
Pre- and postalpha-exposed PM-355 detectors were irradiated using UV laser with different number of pulses (100, 150, 200, 300, and 400). UV laser beam energy of 20mJ per pulse with a pulse width of 9ns was incident on an area of 19.6mm2 of the samples. XRD spectra indicated that for both reference and UV-irradiated samples, the structure is amorphous, but the crystallite size increases upon UV irradiation. The same results were obtained from SEM analysis. Optical properties of PM-355 polymeric solid-state nuclear track detectors were also investigated. Absorbance measurements for all PM-355 samples in the range of 200-400nm showed that the absorption edge had a blue shift up to a certain value, and then, it had an oscillating behavior. Photoluminescence spectra of PM-355 at 250nm revealed a decrease in the broadband peak intensity as a function of the number of UV pulses, while the wavelengths corresponding to the peaks had random shifts.
Application of PM-355 track detectors for investigation of the spatial structure of plasma-proton streams
Abstract The paper describes the use of PM-355 track detectors for studies of spatial structures and energies of pulsed plasma–proton streams generated by an RPI–IBIS accelerator, powered from a 30-kJ condenser bank. Measurements were performed for different operational modes depending on a delay between the gas injection and discharge initiation. To study a spatial structure of the plasma–proton streams we used an ion pinhole camera with PM-355 detectors, placed at the symmetry axis of the experimental chamber, at a distance of 22 cm from electrode ends. To record low-energy (not below 30 keV) protons we did not apply any filter. To select protons of higher energies we used additional absorption filters made of Al-foils of 0.75, 1.5 and 3.0 μm in thickness, which eliminated protons of energies below 125, 210 and 345 keV, respectively. The spatial structure of the proton beams was analyzed and their dependence on the initial gas conditions was investigated.
High energy ion beam modification of polymer films
Abstract Studies on the effects of high energy ion beam irradiation in polymer films are reviewed in this paper. The studies reported in this review suggest exciting research in the field of ion-polymer interaction with impact on electronic transport in disordered systems, dynamical radiation chemistry and novel materials synthesis. p ]High energy ions (> 10 keV amu ) deposit a large amount of energy (several eV atom ) in ionizing the electrons of the target atoms. This results in significant destruction of bonds in the films as a result of which polymers undergo rapid dissociation. Using a quadrupole mass spectrometer, the study of transient emission of molecular species produced by an ion pulse has been shown to yield information about the diffusion and reaction kinetics of various molecules in the polymer. The fact that polymers undergo dissociation and those atoms which form volatile species are selectively depleted from the film could be utilized in producing useful inorganic composites by ion bombardment of polymers. For example, hard SiC composite films have been produced by ion beam irradiation of organo-silicon polymers. Eventually, polymer dissociation leads to a predominantly carbon containing film which exhibits interesting electronic transport properties. Experiments on ion irradiated, pure carbon films indicate that a metallic form of carbon is produced from the polymer films at high irradiation doses. While experiments on disordered conductors have involved the ion beam modification of highly conducting materials to form bad metals (with resistivity, ρ ∼ 10 −3 −10 −4 Ω cm ), comparable bad metals are formed in these experiments starting with insulating materials. There have been, in addition, interesting studies on polymer films using low energy ions (in the ion implantation regime) as well and a brief review of these studies have also been included in this paper.