Micro-crystalline inclusions analysis by PIXE and RBS

A characteristic feature of the nuclear microprobe using a 3 MeV proton beam is the long range of particles (around 70 μm in light matrices). The PIXE method, with EDS analysis and using the multilayer approach for treating the X-ray spectrum allows the chemistry of an intra-crystalline inclusion to be measured, provided the inclusion roof and thickness at the impact point of the beam (Z and e, respectively) are known (the depth of the inclusion floor is Z + e). The parameter Z of an inclusion in a mineral can be measured with a precision of around 1 μm using a motorized microscope. However, this value may significantly depart from Z if the analyzed inclusion has a complex shape. The parameter e can hardly be measured optically. By using combined RBS and PIXE measurements, it is possible to obtain the geometrical information needed for quantitative elemental analysis. This paper will present measurements on synthetic samples to investigate the advantages of the technique, and also on natural solid and fluid inclusions in quartz. The influence of the geometrical parameters will be discussed with regard to the concentration determination by PIXE. In particular, accuracy of monazite micro-inclusion dating by coupled PIXE-RBS will be presented.     

High energy resolution PIXE with high efficiency using the heavy ion microbeam

An X-ray crystal spectrometer using a position sensitive proportional counter combined with tandem microbeam line at Osaka National Research Institute have been developed. This system realizes high energy resolution PIXE analysis using a heavy ion microbeam (E < 6 MeV) with reasonable detection efficiency. The design of the spectrometer, such as detection geometry, detectable energy range and energy resolution, are described. This system was applied to high energy resolution PIXE analysis of Ti, SUS and Si with 2 MeV proton and 5 MeV Si³⁺ focused or collimated beams. The best energy resolution was 2 eV for the Si K line.     

Accelerator mass spectrometry with time-of-flight measurement

A time-of-flight detection system for the measurement of microscopic concentrations of long-lived radioisotopes has been set up at the Munich MP tandem accelerator. The technique allows an unambiguous mass determination for heavy ions up to the actinides. As a first test of the system, the concentration of ¹²⁹I in iodine has been measured for several samples of mineral and biological origin. The smallest ¹²⁹I/¹²⁷I ratios measured were a few times 10⁻¹³. The high sensitivity of the method was achieved by using a 90° injector with a good mass resolution, a special technique of stabilizing the terminal voltage with an auxiliary beam, and a time-of-flight system with a mass resolution of 800.     

Quality control of coins mint using PIXE and RBS analysis

PIXE and RBS analysis is used to investigate the elemental content of modern Lebanese coins, in order to control their minting quality. The coins of interest were 100, 250 and 500 Lebanese Lira (LL), which are mainly bulky metals with or without coated layer. Using 3 MeV protons, proton induced X-ray emission PIXE identified and quantified elements while Rutherford backscattering spectrometry RBS checked the thickness of the coated layer. Indeed, the combination of PIXE and RBS provides a powerful tool to investigate the elemental composition of coins, either modern or ancient. In addition, the experimental protocol was checked by analyzing some other coins of known composition, such as 1-euro and 2-euro.     

PIXE and RBS analysis of Tl-1223 superconducting phase substituted by scandium

Ion beam analysis techniques (IBA) were performed to determine the elemental stoichiometry of superconducting samples of type TlBa₂Ca_2−xSc_xCu₃O_9−δ, with 0 ? x ? 0.6, prepared via solid-state reaction technique. By combining particle induced X-ray emission (PIXE) with Rutherford backscattering spectrometry (RBS), the stoichiometry of the samples is determined. However, the oxygen content is obtained by using non-Rutherford backscattering cross-section at 3 MeV proton beam. Furthermore, the prepared samples were also characterized using X-ray powder diffraction (XRD) and electrical resistivity measurements. The X-ray data indicate that the partial substitution of Ca²⁺ by Sc³⁺ ions does not affect the tetragonal structure of Tl-1223 superconducting phase. The superconducting transition temperatures T_c, determined from electrical resistivity measurements, was found to be highly correlated to the Sc-content.     

An ERD/RBS/PIXE apparatus for surface analysis and channeling

A system for surface analysis, lattice localisation of impurities, defect studies in crystalline solids and routine ERD (elastic recoil detection) is described. The apparatus features a high vacuum chamber, a computer controlled precision goniometer and an energy plus time-of-flight mass discrimination system. First results of channeling/ERD experiments using 15–30 MeV ³⁵Cl beams on silicon crystals implanted with B⁺ and BF₂⁺ are presented, as well as data on the effect of beam induced damage on the boron distribution.     

On artefacts in the secondary ion mass spectrometry profiling of high fluence H+ implants in GaAs

High fluence (>10¹⁷ H/cm²) ion implantation of H in GaAs is suitable for the ion cut process, and produces H bubbles under the surface which may cause blistering. By comparing the destructive depth profiling of these implants by secondary ion mass spectrometry (SIMS) with non-destructive profiling by elastic recoil detection analysis (ERD), we demonstrate that SIMS underestimates total H content by up to a factor of 2 due to undetected H escaping from bubbles during analysis. We also show that the depth of the maximum H concentration from SIMS can be in error by 20% due to large variations in the sputter rate through the profile.     

Evaluation of secondary ion beam transport properties in plasma desorption mass spectrometry

The properties of a time of flight system for ²⁵²Cf plasma desorption mass spectrometry were evaluated by computer simulation. Among the different factors that contribute to mass resolution and detection efficiency of the secondary ions, geometrical misalignments and electric field inhomogeneities are discussed.     

Advances in obsidian hydration dating by secondary ion mass spectrometry: World examples

Since 1960 the potential of obsidian as a chronometer in archaeology has been subjected to several drawbacks and studies. While economical, simple and fast, obsidian hydration dating today is generally unreliable. A novel approach towards obsidian hydration dating, named SIMS-SS, has recently been initiated based on modelling the hydrogen profile acquired by secondary ion mass spectrometry (SIMS), following Fick’s diffusion law, and the rationale of surface saturation (SS) with water molecules. The new nuclear method is presented with significant refinement regarding numerical calculation of age parameters, the suitability criteria of the sampling area and the spectral shape of the concentration dependant H⁺ profile. A reappraisal is applied to thirteen obsidian specimens from all over the world ranging some 100’s to 30,000 years old. The results reinforce the precision and reliability of the SIMS-SS method, enhancing its wide applicability.     

Liquid secondary ion mass spectrometry: I. Molecular ion intensities as a function of primary ion pulse frequency

A liquid matrix and high primary ion currents are employed on a time-of-flight mass spectrometer to produce molecular ions in a manner similar to that employed for fast atom bombardment (FAB) techniques on sector instruments. The primary ion beam is pulsed and the molecular yield is found to depend upon sample concentration, instantaneous primary ion current, and pulse repetition rate. The latter, in particular, indicates that a finite recovery time is required to repair radiation damage from high flux particle beams.     

Development of secondary ion mass spectroscopy using medium energy C60 ion impact

In this paper, we report time-of-flight (TOF) secondary ion mass spectroscopy using primary C₆₀ ions with an energy range from several tens of keV to several hundreds of keV. Application of the spectroscopy to the analysis of a poly(amino acid) film revealed that characteristic peaks, necessary for identification of the amino acid in proteins, show higher intensities for medium energy C₆₀ (120 keV and 540 keV ) impacts than those for low energy C₆₀ (30 keV ) impacts. This finding demonstrates that medium energy C₆₀ ion impacts are useful for highly sensitive characterization of amino acids.     

高能Ar离子辐照PET膜引起的表面改性研究

采用傅立叶转换的红外光吸收技术在反射方式下分析研究了35MeV/u Ar离子辐照半晶质PET膜引起的表面改性及其对吸收剂量的依赖性。结果表明,辐照导致PET膜中与晶态区域相关的吸收带强度随吸收剂量增加普遍减弱,而与非晶区域相关的吸收带强度随吸收剂量增加逐渐增加,表明辐照使PET膜发生了非晶化转变。化学键断裂主要发生在苯环的对位和酯的C－O键上,而苯环的基本结构在整个辐照过程中变化较小。非晶化效应和化学键断裂同时依赖于离子的照射剂量和样品表面的电子能量沉积。此外,在约5．0MGy以上的吸收剂量,辐照还引起了炔端基团的形成,炔端基团浓度随吸收剂量的增加显著增加。对实验结果进行了定性解释。     

High Resolution and Differential PIXE combined with RBS,EBS and AFM analysis of magnesium titanate (MgTiO3) multilayer structures

Thorough structural characterization of deep laying thin film, including the inference of interdiffusion profiles is frequently a complex problem. The use of RBS/PIXE holistic approaches, already shown to represent a powerful method, sometimes faces difficulties if standard experimental procedures are used. In this work, following a series of ⁴He Rutherford backscattering and ¹H elastic backscattering experiments, carried out to study the influence of SrTiO₃ as a possible cladding layer between Pt/TiO₂/SiO₂/(1 0 0)Si substrates and MgTiO₃ films, a simple holistic RBS-PIXE is shown to be not enough for the solution of such a problem. Establishing of the Sr depth profile, was only possible after AFM, High-Resolution EDS PIXE and differential PIXE analysis were carried out. Results, problems faced and conclusions obtained are presented.     

PIXE、SEM与切片技术相结合研究低能离子注入种子的浓度-深度分布

用质子激发X荧光分析和扫描电子显微镜与切片技术相结合对能量为 2 0 0keV的钒离子注入花生后的浓度 -深度分布进行了测定 ,注入剂量为 9× 10 16/cm2 。结果显示 ,钒离子注入花生后的浓度 -深度分布与离子注入金属、半导体中的分布有明显的差异 :离子的射程歧离很大 ,少数离子的射程延伸到很深的区域。这种分布特征可能与植物种子具有疏松的结构有关。     

A new cluster-ion-beam source for secondary ion mass spectrometry (SIMS) using the electrospray of a pure ionic liquid under high vacuum

Electrospray characteristics were studied using a pure room-temperature molten salt (i.e., an ionic liquid) at pressures around 10^?5 Pa as well as at atmospheric pressure. The ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide was tested, which has negligible vapor pressure and high conductivity. During electrospray, the ionic liquid was introduced at a constant flow rate into a stainless-steel capillary (i.d. 30 μm). It was demonstrated that stable electrosprayed currents exceeding ±1 μΑ were continuously produced in both positive and negative modes. The electrosprayed currents in a high vacuum were twice those at atmospheric pressure. It was found that gas pressure rose slightly with increasing electrosprayed currents. Residual gas analysis revealed that gas component at negative mode was different from that at positive mode. Experimental results indicate that vacuum electrospray of pure ionic liquids is applicable to a massive-cluster beam source for SIMS.     

The solid solubility of Fe in α-Zr: A secondary ion mass spectrometry study

Secondary ion mass spectrometry techniques have been used to determine the terminal solid solubility (TSS) of Fe in α-Zr. Single crystals of nominally pure and Fe-doped α-Zr were annealed in the temperature range 770–1100 K to promote equilibration of Fe between surface Zr₃Fe precipitates, or β-Zr(Fe), and α-Zr. The results are fair in overall agreement with a recent investigation, based on thermoelectric power measurements, but they differ in detail. In particular this work indicates two regions of temperature dependence: above 930 K the TSS (ppma) is given by C_Fe = 1.56 × 10¹⁰exp(−1.70 ± 0.05 eV/kT), at lower temperatures a weaker temperature dependence is associated with extrinsic effects. In addition, the eutectoid temperature is shown to lie between 1063 and 1068 K.     

Novel insights in the study of water penetration into polycrystalline UO2 by secondary ion mass spectrometry

Oxygen and water species (e.g., OH⁻, H₂O) diffusion in polycrystalline UO₂ are key parameters to investigate in order to predict spent fuel behaviour in a final repository in the event of exposure to groundwater. In this work, ¹⁸O tracer diffusion is evaluated by means of secondary ion mass spectrometry on a UO₂ pellet exposed to ¹⁸O-labelled water at room temperature for 3 months. Depth profiling up to 22 μm beneath the pellet surface clearly indicates a combination of oxygen diffusion into the UO₂ lattice and water species diffusion along grain boundaries, behaving as high-diffusivity-paths. The relevant coefficients have been estimated around 1.4 × 10⁻²⁴ m² s⁻¹ for lattice diffusion and around 2.3 × 10⁻¹⁶ m² s⁻¹ for grain boundary diffusion.     

Structure of ion tracks in ceria irradiated with high energy xenon ions

Structure and accumulation behavior of ion tracks in CeO₂ irradiated with 200 MeV Xe ions were examined by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) to obtain fundamental knowledge on the microstructure evolution induced by fission fragments in nuclear fuels and transmutation targets, which is of importance for the development of advanced fuel/target materials at high burn-up conditions. Bright-field (BF) TEM images of ion tracks from an inclined direction showed Fresnel contrast along penetrating path of incident ions. The signal intensity of high-angle annular dark-field (HAADF) STEM images was decreased at the core damage region of ion tracks along the path of ions, revealing the reduction of atomic density inside the ion track. Preferential formation of smaller and larger ion tracks was observed at a high ion fluence of 1 × 10¹⁴ cm⁻² compared to a low ion fluence of 1 × 10¹¹ cm⁻². Results were discussed due to the coalescences and incomplete recovery of the core damage regions during the overlap of high density electronic excitation damage, which is induced during the repetition of the formation and recovery of ion tracks within an influence region.     

固体气泡损伤探测器探测高能重离子的研究

用高能重离子Ar和C进行的实验表明：（1）高能重离子可以在固体气泡损伤探测器中产生径迹,重离子径迹呈直线形,由一连串微小气泡组成;（2）固体气泡损伤探测器探测重离子具有阈特性,阈的实质近似为临界能量损失率（dE／dX）C,这一阈特性与蚀刻径迹探测器类似。固体气泡损伤探测器的阈值为（dE／dX）c=2220MeV／g·cm2,可用于重离子物理、宇宙射线和宇宙暗物质探测以及癌症治疗模拟等领域。