Search results for "Ion track"

Why are hydrogen ions best for MeV ion beam lithography?

2013

The exposure characteristics of poly-(methyl methacrylate) (PMMA) for 2MeV ^1H^+, 3MeV ^4He^2^+ and 6MeV ^1^2C^3^+ have been investigated. The samples were characterised using Atomic Force Microscopy (AFM), optical microscopy and Raman spectroscopy. Development was carried out using a 7:3 propan-2-ol:H"2O mixture to determine clearing and cross-linking fluences. It was found that protons had a considerably wider tolerance to exposure variations and a smaller span of doses within the ion track. Furthermore, the void formation and consequent stress-induced surface roughening were smaller for protons. For all ions, the C?C bond Raman signal increased continuously with dose and fluence, even we…

Excitation of different chromium centres by synchrotron radiation in MgO:Cr single crystals

2015

The excitation spectra for the emissions of chromium-containing centres have been measured at 10 K using synchrotron radiation of 4–32 eV in MgO single crystals with different content of Cr$^{3+}$ (5–850 ppm) and Ca$^{2+}$ impurity ions. Both virgin crystals and the samples preliminarily irradiated with x-rays at 295 K have been studied. The role of complex chromium centres containing two Cr$^{3+}$ and a cation vacancy (sometimes nearby a Ca$^{2+}$ ion) on the luminescence processes and the transformation/creation of structural defects has been analysed. Such anharmonic complex centres could serve as the seeds for the creation of 3D defects that facilitate the cracking and brittle destructi…

CdTe Nanocrystal Synthesis in SiO 2 /Si Ion‐Track Template: The Study of Electronic and Structural Properties

2020

Characterisation of Apatites as Potential Uranium Reference Materials for Fission-track Dating by LA-ICP-MS

2015

We report homogeneity tests on large natural apatite crystals to evaluate their potential as U reference materials for apatite fission-track (AFT) thermochronology by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The homogeneity tests include the measurements of major element concentrations by electron probe microanalysis (EPMA), whereas for U concentration, isotope dilution (ID) ICP-MS and laser ablation (LA) ICP-MS were employed. Two apatite crystals are potential reference materials for LA-ICP-MS analysis: a 1 cm3 fraction of a Durango crystal (7.5 μg g−1 U) and a 1 cm3 Mud Tank crystal (6.9 μg g−1 U). The relative standard deviation (1 RSD) of the U concentrat…

Improving the Design of Ion Track-Based Biosensors

2018

In the last decade we had developed new types of biosensors, by cladding the inner walls of transparent etched swift heavy ion tracks in thin polymer foils with enzymes. The enzymatic reaction products of appropriate analytes penetrating into narrow tracks are enriched in the track’s confinement, and they change the electrical track properties if their charge states differ from those of the analytes. It was yet unknown how to design these sensors so that their best efficiency and highest possible sensitivity is achieved. This requires the accurate knowledge of the optimum track radius and the degree of product enrichment within the tracks. These questions were answered by appropriate experi…

LiF crystals irradiated with 150MeV Kr ions: Peculiarities of color center creation and thermal annealing

2013

Abstract Color centers in LiF crystals are studied under irradiation at room temperature with 150 MeV Kr ions in the fluence (Φ) range of 1010–1014 ions/cm2 with a beam current density of 10, 50, and 100 nA/cm2, corresponding to flux of 4.46 × 109, 2.23 × 1010 and 4.46 × 1010 ions/(cm2 × s), respectively. At Φ ⩾ 3 × 1012 ions/cm2 besides F and Fn centers also charged F 3 + centers are created. Thermal annealing of irradiated LiF crystals with Φ ⩾ 1013 ions/cm2 at 400 K leads to a decrease of F centers (due to annihilation with H centers) and an enhancement of complex Fn color centers (neutral and charged) due to interaction with thermally activated anion vacancies. Annealing LiF crystals at…

Color centers and nanodefects in LiF crystals irradiated with 150MeV Kr ions

2012

Abstract The modifications of structure, optical and nano-mechanical properties of LiF crystals after irradiation with 150-MeV Kr +14 ions at a fluence of 6 × 10 12  ions cm −2 have been studied using optical absorption spectroscopy, scanning electron and atomic force microscopy, and nanoindentation. Optical spectroscopy shows the saturation of F centers and a comparatively high number of F n centers. AFM and SEM imaging reveals a nanostructured region with columnar nanocrystallites (size 30–90 nm). Nanostructuring occurs in depths up to 10 μm, where the ion energy loss surpasses a critical threshold of about 10 keV/nm. At a lower energy loss a zone enriched with dislocations is observed. S…

Investigation of heavy ion tracks in LiF crystals by dislocation mobility method

2008

Abstract The track damage created in LiF by swift heavy ions was studied using methods of dislocation mobility and track etching. The crystals were irradiated with Bi and Pb ions of a specific energy of 11 MeV/u at fluences between 10 7 and 10 10  cm −2 . The measurements on cross-sections cleaved parallel to the irradiated surface showed continuity of the track etching for the depth up to 70% of the ion range. In deeper layers, numerous etch pits had a flat-bottomed shape indicating the discontinuities of the track structure. At this stage, a decrease of the ion-induced effect in dislocation mobility was observed. The observed reduction of the efficiency of ion tracks as obstacles for disl…

Ion track template technique for fabrication of ZnSe2O5 nanocrystals

2020

The work was performed under the grant of the Ministry of Education and Science of the Republic of Kazakhstan AP05134367 and Latvian grant lzp

Thin film growth into the ion track structures in polyimide by atomic layer deposition

2017

Abstract High-aspect ratio porous structures with controllable pore diameters and without a stiff substrate can be fabricated using the ion track technique. Atomic layer deposition is an ideal technique for depositing thin films and functional surfaces on complicated 3D structures due to the high conformality of the films. In this work, we studied Al2O3 and TiO2 films grown by ALD on pristine polyimide (Kapton HN) membranes as well as polyimide membranes etched in sodium hypochlorite (NaOCl) and boric acid (BO3) solution by means of RBS, PIXE, SEM-EDX and helium ion microcopy (HIM). The focus was on the first ALD growth cycles. The areal density of Al2O3 film in the 400 cycle sample was det…