Ion Beam Analysis Techniques Research Articles

IBA techniques: Examples of useful combinations for the characterisation of cultural heritage materials

For many years, ion beam analysis techniques have successfully been used to the study of cultural heritage objects. The chemical composition of work art is usually determined by PIXE, but in many cases, RBS and/or PIGE can provide useful complementary information. RBS gives information about the depth distribution and concentration in light elements, such as carbon and oxygen. In the past years, the experimental facilities at the AGLAE (Accélérateur Grand Louvre d’Analyse Élémentaire) accelerator has been progressively developed in order to apply simultaneously PIXE, PIGE and RBS under optimal conditions using an external beam. This combination is now routinely used for point analyses or mappings. In this contribution, we present several examples of applications: manufacturing technology of lustre-decorated ceramics and silver plating, control of altered or restored surfaces, and quantification of organic phase in painting and bone. The final conclusion is that the association of PIXE with RBS is very attractive for the investigation of cultural heritage objects, in particular of materials containing both mineral and organic components or possessing a multilayered structure. The first results of the production of monochromatic X-rays for radiography purposes by PIXE are also presented.

A review of external microbeams for ion beam analyses

Ion microbeam facilities are analytical tools with high spatial resolution exploiting MeV ion beams. The interactions of beam particles with atoms and nuclei of the target induce the emission of characteristic radiation, the energy of which provides signatures of the compositional and/or structural properties of the target; Ion-Beam Analysis (IBA) techniques, based on the detection of such radiation, enable characterisation of samples of interest, e.g. in material and earth sciences, cultural heritage, biology, medicine, and environmental studies. External beams, obtained by extracting the particles into the atmosphere through a thin window, have many attractive features, e.g. non-destructive/non-invasive analysis and ease of working, so many laboratories have dedicated beam-lines to ex-vacuo IBA analyses. External microprobes have made it possible to obtain probes in the micron range by adopting strong focusing lenses, ultra-thin windows for beam extraction, and short/ultra-short external path of beam particles in light gases; they have also made possible the use of new external IBA techniques, e.g. BS, ERDA, STIM, and IBIC. By adopting systems to raster scan the beam over the sample, imaging capabilities have also become available for ex-vacuo analysis. External scanning microprobes + IBA techniques have enabled the characterisation of samples with high spatial resolution, comparable with that achievable in-vacuum for thick samples, avoiding sample damage.

Fine particle characterisation, source apportionment and long-range dust transport into the Sydney Basin: a long term study between 1998 and 2009

Ion beam analysis techniques have been used to characterise fine particle (PM2.5) pollution in the Sydney Basin between 1 July 1998 and 31 December 2009. Nearly 1 200 filters were obtained and analysed for more than 21 different chemical species from hydrogen to lead. Positive matrix factorisation was then applied to this significant database to determine 7 different source fingerprints and their contributions to the total PM2.5 mass. Most of these sources originated in the Sydney Basin, however there were significant windblown soil sources that originated not just from desert regions in central Australia but also from large agricultural regions around 500 km south west of the Basin. This long range transport of fine dust was tracked using hourly back trajectories for every sampling day during the study period and showed that 33% of extreme dust events were probably originating from agricultural regions and not the central desert regions of Australia as first thought.

4He+ Ion Beam Irradiation Induced Modification of Poly(dimethylsiloxane). Characterization by Infrared Spectroscopy and Ion Beam Analytical Techniques

In this study we investigated the chemical and surface wettability changes of poly(dimethylsiloxane) (PDMS) induced by a 2.0 MeV He(+) beam irradiation. The chemical changes created in PDMS were characterized by universal attenuated total reflectance infrared (UATR-FTIR) spectroscopy, while the changes of the wettability were determined by contact angle measurements. In a separate analysis, hydrogen depletion was also investigated with a 1.6 MeV He(+) beam by applying the elastic recoil detection analysis (ERDA) and Rutherford backscattering spectrometry techniques simultaneously. The ERDA results showed that the hydrogen content of PDMS decreased irreversibly, which means that volatile products were formed under radiolysis, such as hydrogen or methane. The results were completed with UATR-FTIR measurements. We propose a complete reaction mechanism for the processes taking place in PDMS. These ion beam induced processes, such as chain scissions, cross-linking, and depletion of small molecular weight fragments, lead to the formation of a silica-like final product (SiO(x)). The significant chemical changes at the surface influence the wettability of PDMS, making it considerably more hydrophilic. The penetration depth of the 2.0 MeV He(+) ions is significantly higher compared to that of other surface modification techniques, which makes the modified layer thick and homogeneous; on the other hand, it is easily controllable by the energy of the incident ions.

Study of emission episodes of urban aerosols by ion beam analytical techniques

The quantitative elemental composition and morphology of over 500 atmospheric aerosol particles were determined by nuclear microscopy and scanning electron microscopy (SEM). The samples originated from eight sampling campaigns, when hourly variation and sources of the urban aerosol elemental components were studied in Debrecen between 2007 and 2010. Aerosol which could be connected to heavy metal pollution episodes and high aerosol pollution levels deposits were selected for the nuclear microprobe study.Ion beam analytical methods (micro-PIXE and STIM) provided the elemental composition of coarse (particles with aerodynamic diameter between 2.5 and 10μm) aerosols while the morphology of the different particle types was determined by SEM.Through the elemental composition, elemental correlations and morphology different particle types were identified and attributed to different anthropogenic sources like biomass burning, oil combustion, traffic or industry.

Damage and deuterium retention in LiAlO2 single crystals irradiated with deuterium ions using ion-beam techniques and optical absorption measurements

Ion beam analysis techniques and optical absorption measurements were employed to quantitatively examine the damage and deuterium retention in LiAlO2 single crystals irradiated with 10keV D2+. Rutherford backscattering spectrometry in channeling geometry revealed that the lattice atoms were disordered by the incident deuterium ions in the ratio O/Al of 2.5. Elastic recoil detection analysis showed that all the incident deuterium ions were retained near the end of their trajectories with a maximum concentration of 0.7 D/Al at room temperature. The depth profiles of the disordered atoms were nearly identical to those of the retained deuterium atoms. The release of the retained deuterium atoms and the annihilation of the ion-induced color centers, which contributed to an optical absorption band at 5.25eV, were observed in the same temperature range. A correlation was established between the oxygen vacancies and the retained deuterium atoms.

Modulation of Field Emission Properties of ZnO Nanorods During Arc Discharge

Zinc oxide (ZnO) nanorods have been synthesized via the arc discharge method. Different oxygen partial pressures were applied in the arc discharge chamber to modulate the field emission properties of the as-synthesized ZnO nanorods. Scanning electron microscopy (SEM) was carried out to analyze the morphology of the ZnO nanorods. The ion beam analysis technique of proton induced X-ray emission (PIXE) was performed to probe the impurities in ZnO nanorods. SEM images clearly revealed the formation of randomly oriented ZnO nanorods with diameters between 10-50 nm. It was found that the morphology and the electrical properties of the ZnO nanorods were dependent on the oxygen partial pressure during arc discharge. In addition enhanced UV-sensitive photoconductivity was found for ZnO nanorods synthesized at high oxygen partial pressure during arc discharge. The field emission properties of the nanorods were studied. The turn-on field, which is defined at a current density of 10 microA cm(-2), was about 3 V microm(-1) for ZnO nanorods synthesized at 99% oxygen partial pressure during arc discharge. The turn-on field for ZnO nanorods increased with the decrease of oxygen partial pressure during arc discharge. The simplicity of the synthesis route coupled with the modulation of field emission properties due to the arc discharge method make the ZnO nanorods a promising candidate for a low cost and compact cold cathode material.

Stoichiometry evolution of polyethylene terephtalate under 3.7 MeV He + irradiation

A 3.7 MeV He + ion beam was simultaneously used for Polyethylene Terephtalate (PET) film degradation and characterization. To enhance the potentialities of the characterization method, a multi-detector Ion Beam Analysis (IBA) technique was used. The stoichiometry change of the PET target following the irradiation is quantified at a beam fluence varying between 7 × 10 13 and 1.8 × 10 16 He + cm −2. The damage induced in PET films by He + bombarding was analyzed in-situ simultaneously through Rutherford Backscattering Spectrometry (RBS), Particle Elastic scattering Spectrometry (PES) and Hydrogen Elastic Recoil Detection (ERD). Appropriate experimental conditions for the observation of absolute changes in composition and thickness during irradiation were determined. The oxygen and carbon content evolution as a function of the ion fluence was monitored by He + backscattering whereas the hydrogen content was measured by H( α, H) α collisions in which both the scattered He + ions and the recoiling H could be observed. The present study reveals that, at the highest fluence 1.8 × 10 16 He + cm −2, the PET films have lost approximately 15% of the carbon, more than 45% of the hydrogen and 85% of the oxygen of the amount contained in the pristine sample. The energy shift of recoiling H + ions at a forward angle 45° was followed in order to study the mass loss effect. The experimental results are consistent with the bulk molecular recombination model. Based on the results, hydrogen, oxygen and carbon release cross sections are determined. For hydrogen, comparison with deuteron irradiation indicates a cross section linear dependence on the stopping power.

Differential cross sections for the 11B( p, αo) 8Be and 11B( p, p0) 11B reactions, suitable for ion beam analysis

Boron depth profiling presents strong analytical challenges for all Ion Beam Analysis (IBA) techniques. In the past, both the 11B( p, α o) 8Be (NRA) and the 11B( p, p 0) 11B (EBS) reactions have been proposed and they seem to be quite suitable for analytical purposes. Nonetheless, both reactions have not been adequately studied in literature (as far as data suitable for material analysis in the backscattering geometry are concerned). Moreover, the existing datasets are relatively discrepant. In an attempt to clarify the situation, both reactions were studied in the present work between 135° and 160°, in steps of 5°, for the proton beam energy range between 2.2 and 4.2 MeV, in steps of 50 keV. An attempt to explain the occurring results in the framework of the resonance mechanism is also presented, along with a comparison with previously published data.

Nitrogen and neon retention in plasma-facing materials

Tungsten plate was exposed in the TEXTOR tokamak during nitrogen-assisted discharges. In order to determine material mixing on tungsten, the plate was examined ex situ with ion beam analysis techniques including time-of-flight heavy ion elastic recoil detection analysis and also with X-ray photoelectron spectroscopy. Nitrogen content in the range from 1.3×1015 to 3.4×1015cm−2 is measured in the outermost surface layer (20nm) of the W plate. Photoelectron spectroscopy detects nitrogen both in the elemental and compound form, i.e. tungsten nitride (WN/W2N). Nitrogen is measured even in hot areas free from deuterium. Also neon co-implantation into the plasma-facing components has been identified following Ne-cooled pulses.

The Guelph PIXE software package IV

Following the introduction of GUPIXWIN in 2005, a number of upgrades have been made in the interests of extending the applicability of the program. Extension of the proton upper energy limit to 5 MeV facilitates the simultaneous use of PIXE with other ion beam analysis techniques. Also, the increased penetration depth enables the complete PIXE analysis of paintings. A second database change is effected in which recently recommended values of L-subshell fluorescence and Coster–Kronig yields are adopted. A Monte Carlo code has been incorporated in the GUPIX package to provide detector efficiency values that are more accurate than those of the previous approximate analytical formula. Silicon escape peak modeling is extended to the back face of silicon drift detectors. An improved description of the attenuation in dura-coated beryllium detector windows is devised. Film thickness determination is enhanced. A new batch mode facility is designed to handle two-detector PIXE, with one detector measuring major elements and the other simultaneously measuring trace elements.

Tolerance to proton irradiation in the eutardigrade Richtersius coronifer – a nuclear microprobe study

Purpose: The tardigrade Richtersius coronifer has previously been shown to tolerate very high doses of low linear energy transfer (low-LET) radiation (gamma rays). The purpose of this study was to extend our knowledge on radiation tolerance in this species by investigating the dose-response to high-LET radiation in terms of protons.Materials and methods: Dehydrated tardigrades of the species R. coronifer were irradiated with 2.55 MeV (megaelectronvolts) protons at doses ranging from 500 gray (Gy) to 15,000 Gy, to investigate the dose-viability relationship. In addition, a focused proton microbeam was utilised to determine the areal mass distribution, using the ion beam analytical technique STIM (Scanning Transmission Ion Microscopy).Results: The experiment suggests that R. coronifer is unaffected by doses of proton irradiation up to 10,000 Gy, but shows very little viability at higher doses. The STIM analysis revealed that the thickness of the dehydrated tardigrades exceeds 150 μm, and that a fraction of the protons may not be fully absorbed.Conclusion: Our results are in line with previous studies of exposure to high-LET radiation in tardigrades, indicating that these animals are equally or even more tolerant to high-LET compared to low-LET gamma radiation. The physiological background to this remarkable result is currently unknown, but deserves investigation.

Quantitative analysis of a metalloprotein compositional stoichiometry with PIXE and PESA

An absolute measurement of the heavy element concentrations in a dried sample of aqueous protein solution has been combined with the absolute measurement of protein molecular concentration in the same sample. The ratio of these two measurements yields the metal-to-protein compositional stoichiometry of the metalloprotein. This combination of two Ion Beam Analysis techniques (Particle-Induced X-ray Emission and Proton Elastic Scattering Analysis) allows quantitative assessment of the metal atom to protein ratio in metalloproteins without direct measurement of sulfur atoms within the protein for the first time. While these results only demonstrate success with a single well-known metalloprotein, this combination of measurement ratios holds promise for future Ion Beam Analysis studies of metalloproteins.

UHV-ERDA investigation of NEG coatings

Abstract Non-evaporable getter (NEG) coatings are widely used in large vacuum systems such as particle accelerators. Since NEG coatings produced at the GSI Helmholtzzentrum fur Schwerionenforschung have a finite thickness of typically 1 μm, ion beam analysis techniques such as ERDA and RBS are the methods of choice to study element and depth-resolved evolution of the getter film during gas pumping. The film thickness and stoichiometry can be determined by RBS while ERDA is sensitive to lighter elements such as carbon, nitrogen and oxygen, the main residual gas components of a vacuum environment. In this work we first present exsitu and insitu measurements of NEG thin films using ERDA. For the investigation of the pumping speed and capability of the getter films, we have used a vacuum test chamber where getter coated samples can be activated and saturated in a very controlled way. Afterwards, depth distributions of the pumped gas components have been measured using ERDA. To study the gas components in NEG coatings online, i.e., during activation or pumping, we have set up an ERDA system working at vacuum pressures down to 10 - 11 mbar . A special target heater system allows to activate the getter coatings insitu at typical temperatures between 180 and 300 °C in a UHV environment with tolerable influence to the total and partial gas pressure. With this UHV-ERDA setup, a temperature dependent diffusion process of gas components into the getter material could be analyzed for the first time.

A new mapping acquisition and processing system for simultaneous PIXE-RBS analysis with external beam

Abstract The combination of ion beam analysis techniques is particularly fruitful for the study of cultural heritage objects. For several years, the AGLAE facility of the Louvre laboratory has been implementing these techniques with an external beam. The recent set-up permits to carry out PIXE, PIGE and RBS simultaneously on the same analyzed spot with a particle beam of approximately 20 μm diameter. A new mapping system has been developed in order to provide elemental concentration maps from the PIXE and RBS spectra. This system combines the Genie2000 spectroscopy software with a homemade software that creates maps by handling acquisition with the object position. Each pixel of each PIXE and RBS maps contains the spectrum normalised by the dose. After analysing each pixel of the PIXE maps (low and high energy X-ray spectra) with the Gupixwin peak-fitting software, quantitative elemental concentrations are obtained for the major and trace elements. This paper presents the quantitative elemental maps extracted from the PIXE spectra and the development of RBS data processing for light element distribution and thin layer characterization. Examples on rock painting and lustrous ceramics will be presented.

Contribution of ion beam analysis methods to the development of second generation high temperature superconducting wires

Abstract One of the crucial steps in the second generation high temperature superconducting wire program was development of the buffer-layer architecture. The architecture designed at the Superconductivity Technology Center at Los Alamos National Laboratory consists of several oxide layers wherein each layer plays a specific role, namely: nucleation layer, diffusion barrier, biaxially textured template, and intermediate layer providing a suitable lattice match to the superconducting Y1Ba2Cu3O7 (YBCO) compound. This report demonstrates how a wide range of ion beam analysis techniques (SIMS, RBS, channeling, PIXE, PIGE, NRA and ERD) was employed for analysis of each buffer layer and the YBCO film. These results assisted in understanding of a variety of physical processes occurring during the buffer layer fabrication and helped to optimize the buffer-layer architecture as a whole.

Ion beam characterization of Fe-implanted GaN

Abstract Fe ion implantation in GaN has been investigated by means of ion beam analysis techniques. Implantations at an energy of 150 keV and fluences ranging from 2 × 10 15 to 1 × 10 16 cm −2 were done, both at room temperature and at 623 K. Secondary Ions Mass Spectrometry was used to determine the Fe implantation profiles, whereas Rutherford Backscattering in channeling conditions with a 2.2 MeV 4 He + beam allowed us to follow the damage evolution. Particle Induced X-ray Emission in channeling conditions with a 2 MeV H + beam was employed to study the lattice location of Fe atoms after implantation. The results show that a high fraction of Fe-implanted atoms are located in high symmetry sites in low fluence implanted samples, where the damage level is lower, whereas the fraction of randomly located Fe atoms increases by increasing the fluence and the resulting damage. Moreover, dynamical annealing present in high temperature implantation has been shown to favor the incorporation of Fe atoms in high symmetry sites.

Damage and microstructure evolution in GaN under Au ion irradiation

Damage and microstructure evolution in gallium nitride (GaN) under Au+ ion irradiation has been investigated using complementary electron microscopy, secondary ion mass spectrometry and ion-beam analysis techniques. Epitaxially-grown GaN layers (2 µm thick) have been irradiated by 2.0 MeV Au ions to 1.0 × 1015 and 1.4 × 1015 cm−2 at 155 K and to 7.3 × 1015 cm−2 at 200 K. The irradiation-induced damage has been analysed by Rutherford backscattering spectroscopy in a channelling direction (RBS/C). For a better determination of the ion-induced disorder profile, an iterative procedure and a Monte Carlo code (McChasy) are combined to analyse the ion channelling spectra. With increasing irradiation dose, separated amorphous layers develop from the sample surface and near the damage peak region. Formation of large nitrogen bubbles with sizes up to 70 nm is observed in the buried amorphous layer, while the surface layer contains small bubbles with a diameter of a few nanometres due to significant nitrogen loss from the surface. Volume expansion from 3% to 25% in the irradiated region is suggested by cross-sectional transmission electron microscope and RBS/C measurement. The anomalous shape of the Au distributions under three irradiations indicates out-diffusion of Au towards the sample surface. The results from the complementary techniques suggest that nitrogen is retained in the damaged GaN where the crystallinity is preserved. Once the amorphous state is reached in the surface region, GaN starts to decompose and nitrogen escapes from the surface. Furthermore, experimental results show considerable errors in both the disorder profile and the ion range predicted by the Stopping and Range of Ions in Matter code, indicating a significant overestimation of electronic stopping powers of Au ions in GaN.

Targeting Ion Beam Analysis techniques for gold artefacts

The present study discusses the best experimental conditions for the quantitative analysis of gold jewellery artefacts by ion beam techniques (PIXE, RBS, PIGE and NRA). Special attention is given to the detection of enhancement or depletion below the surface, down to 10 microns, without any sampling or destruction. PIXE is certainly the most interesting technique for this purpose and the optimal geometrical arrangement of the experiment is described: orientation of the incident beam relative to sample surface, selection of the characteristic signals, use of reference material, choice of the detector and incident particle energy and type, computation of absorption and secondary fluorescence effects.

Characterisation and source apportionment of fine particulate sources at Hanoi from 2001 to 2008

PM 2.5 particulate matter has been collected on Teflon filters every Sunday and Wednesday at Hanoi, Vietnam for nearly eight years from April 2001 to December 2008. These filters have been analysed for over 21 different chemical species from hydrogen to lead by ion beam analysis techniques. This is the first long term PM 2.5 dataset for this region. The average PM 2.5 mass for the study period was (54 ± 33) μg m −3, well above the current US EPA health goal of 15 μg m −3. The average PM 2.5 composition was found to be (29 ± 8)% ammonium sulfate, (8.9 ± 3.3)% soil, (28 ± 11)% organic matter, (0.6 ± 1.4)% salt and (9.2 ± 2.8)% black carbon. The remaining missing mass (25%) was mainly nitrates and absorbed water. Positive matrix factorisation techniques identified the major source contributions to the fine mass as automobiles and transport (40 ± 10)%, windblown soil (3.4 ± 2)%, secondary sulfates (7.8 ± 10)%, smoke from biomass burning (13 ± 6)%, ferrous and cement industries (19 ± 8)%, and coal combustion (17 ± 7)% during the 8 year study period.