Professor Chris Jeynes

Accurate elemental depth profiling by IBA is of great value to many modern thin-film technologies. IBA is a quantitative analytical technique now capable of traceable accuracy below 1%. In this chapter we describe sources of errors in data collection and analysis (pitfalls) greater than about 1/4%.

In this study the impact of the defect tails generated by germanium implantation into n-type silicon wafers on the deep energy states, the doping profiles and mobilities, are investigated. 100 mm (100) silicon wafers with a base doping concentration of 3×1015/cm3 have been Implanted with 80 keV germanium on the Danfysik DF1090 high current implanter using instantaneous current density of 5 μA/cm2-95 μA/cm2, which correspond to power loading values of 0.4 and 7.6 W/cm2 respectively. Channelling Rutherford Backscattering analysis of a wafer implanted with 1×1016 Ge/cm2 and a dose rate of 80 μA/cm2 indicates a defect tail extending to 0.65 μm compared with 0.35 μm from a similar implant using 20 μA/cm2. Deep Level Transient Spectroscopy (DLTS) measurements of samples implanted with 3×1014 Ge/cm2 followed by a regrowth anneal of 700 °C for 20 mins reveal a high concentration of deep levels beyond the projected range of germanium of 58 nm at depths extending from 0.15 μm to depths greater than 0.4 μm. The main peak indicate a deep level at 0.35 eV. The increase in the dose rate from 5 μA/cm2 to 95 μA/cm2 is accompanied by a 5 times reduction of the 0.35 eV trap concentration. This difference could be attributed to the dynamic annealing effects during the implant using 95 μA/cm2.

An understanding of the effect of cumulative radiation damage on the integrity of ceramic wasteforms for plutonium and minor actinide disposition is key to the scientific case for safe disposal. Alpha recoil due to the decay of actinide species leads to the amorphisation of the initially crystalline host matrix, with potentially deleterious consequences such as macroscopic volume swelling and reduced resistance to aqueous dissolution. For the purpose of laboratory studies the effect of radiation damage can be simulated by various accelerated methodologies. The incorporation of short-lived actinide isotopes accurately reproduces damage arising from both alpha-particle and the heavy recoil nucleus, but requires access to specialist facilities. In contrast, fast ion implantation of inactive model ceramics effectively simulates the heavy recoil nucleus, leading to amorphisation of the host crystal lattice over very short time-scales. Although the resulting materials are easily handled, quantitative analysis of the resulting damaged surface layer has proved challenging. In this investigation, we have developed an experimental methodology for characterisation of radiation damaged structures in candidate ceramics for actinide disposition. Our approach involves implantation of bulk ceramic samples with 2 MeV Kr+ ions, to simulate heavy atom recoil; combined with grazing incidence X-ray absorption spectroscopy (GI-XAS) to characterise only the damaged surface layer. Here we present experimental GI-XAS data acquired at the Ti and Zr K-edges of ion implanted zirconolite, as a function of grazing angle, demonstrating that this technique can be successfully applied to characterise only the amorphised surface layer. Comparison of our findings with data from metamict natural analogues provide evidence that heavy ion implantation reproduces the amorphous structure arising from naturally accumulated radiation damage.

The effects of high dose Ar ion irradiation on immiscible AlN/TiN multilayered structures were studied. The structures with 30 alternate layers of a total thickness of ~ 260 nm were deposited by reactive sputtering on (100) Si wafers. Individual layer thickness was ~ 8 nm AlN and ~ 9.3 nm TiN. Irradiation was done with 180 keV Ar ions to 1 × 10-8 × 10 ions/cm, with the projected range around mid-depth of the structures. It was found that the highest applied dose induced a considerable intermixing, where the growing TiN grains consume the adjacent AlN layers, transforming partly to (TiAl)N phase. Intermixing occurs due to a high contribution of collision cascades, which was not compensated in demixing by chemical driving forces. However, a multilayered structure with relatively flat surface and interfaces is still preserved, with measured nano-hardness value above the level for the as-deposited sample. The results are compared to other systems and discussed in the light of the existing ion beam mixing models. They can be interesting towards better understanding of the processes involved and to development of radiation tolerant coatings. © 2012 Elsevier B.V. All rights reserved.

Analysis using MeV ion beams is a thin film characterisation technique invented some 50 years ago which has recently had the benefit of a number of important advances. This review will cover damage profiling in crystals including studies of defects in semiconductors, surface studies, and depth profiling with sputtering. But it will concentrate on thin film depth profiling using Rutherford backscattering, particle induced X-ray emission and related techniques in the deliberately synergistic way that has only recently become possible. In this review of these new developments, we will show how this integrated approach, which we might call “total IBA”, has given the technique great analytical power.

The biblical book of Psalms is discussed from an historical point of view. Who were the original poets, when did they write and what did they intend by their poetry? The short answer to these questions is: "we don't know for sure", but the long answer is considerably more interesting. This poetry from three millennia ago has changed the world, and has the potential to continue changing it.

Ion implantation of fluorine and silicon ions into stainless steel heater alloys inhibits the accumulation of CaSO4 deposits when used in an saturated aqueous solution of 1.6 g/l concentration. This anti-fouling action leads to an increase in the heat transfer coefficient by more than 100% under a heat flux of 200 kW/m2 and 200% under a heat flux of 100 kW/m2 when compared to unimplanted heater elements. Heat transfer data indicate that following a heating cycle of 4000 minutes a thick layer of CaSO4 deposit remain on unimplanted heater surfaces. Similar CaSO4 deposits also formed on the implanted alloys initially but did not remain after 1000 minutes causing a significant recovery in the heat transfer coefficient. Ion implanting these alloys leads to surface energy reduction and hence the anti-fouling action observed.

Penetration of a nanochannel mask by 190keV Co ions is tested for the purpose of achieving laterally modulated ion implantation into a SiO thin film on a Si substrate. A 2D-nanoporous membrane of anodic aluminum oxide (AAO) is chosen as the mask. Criteria and challenges for designing the mask are presented. Implantation experiments through a mask with pore diameter of 125 nm and inter-pore distance of 260 nm are carried out. Cross-sectional TEM (XTEM) is shown as an ideal tool to assess depth distribution and lateral distribution of implanted ions at the same time, complemented by Rutherford backscattering spectroscopy. Using energy dispersive x-ray spectroscopy linescans, a Co distribution with lateral modulation is found at 120 nm below the oxide surface. First experiments in converting the atomic distribution of Co to discrete nanoparticles by in-situ TEM annealing are presented. © 2012 Materials Research Society.

Buried layers of CoSi2 have been fabricated by implanting high doses of energetic Co atoms, into single crystal (100) silicon substrates maintained at approximately 550-degrees-C. For doses greater-than-or-equal-to 4 x 10(17) Co-59+ cm-2, at 350 keV, a continuous buried layer of CoSi2 grows epitaxially during implantation. For lower doses the 'as implanted' structure is discontinuous and consists of discrete precipitates of both A- and B- type CoSi2. After annealing at 1000-degrees-C for 30 minutes a continuous buried layer of stoichiometric CoSi2 is produced for doses greater-than-or-equal-to 2 x 10(17) Co-59+ cm-2, at 200 keV and greater-than-or-equal-to 4 x 10(17) Co-59+ cm-2, at 350 keV. For lower doses the synthesised layer is discontinuous and consists of discrete octahedral CoSi2 precipitates which are aligned with the matrix (A-type).

“Total-IBA” implies the synergistic use of multiple IBA techniques. It has been claimed that Total–IBA inherits the accuracy of the most accurate IBA technique used. A specific example is now given of this where (in vacuo) EBS/PIXE of a glass sample uniform in depth is validated against absolutely calibrated EPMA of the same sample. The EPMA results had a mass closure gap of 2.0 ± 0.6 wt%; the full PIXE analysis determined the composition of this missing 2 wt%. The PIXE calibration was against a single certified glass sample, with uncertainties per line ~10%. Benchmarking also demonstrates ~10% underestimation of the Si scattering cross-section at proton energies ~3 MeV. But the Total-IBA determination of the silica content had a low standard uncertainty of about 2%. This is due to the strong constraints of both the chemical prior and also the mass closure properties of the EBS. Irradiation-induced sodium migration in this soda-lime glass is explored.

The electrical characteristics of gallium-doped zinc oxide (ZnO:Ga) thin films prepared by rf diode sputtering were altered via nitrogen implantation by performing two implants at 40 keV and 80 keV with doses of 1×1015 and 1×1016 cm−2 to achieve a p-type semiconductor. An implantation of 1×1015 cm−2 N+-ions yielded a p-type with hole concentrations 1017–1018 cm−3 in some as-implanted samples. The films annealed at temperatures above 200°C in O2 and above 400°C in N2 were n-type with electron concentrations 1017–1020 cm−3. The higher nitrogen concentration (confirmed by SRIM and SIMS), in the films implanted with a 1×1016 cm−2 dose, resulted in lower electron concentrations, respectively, higher resistivity, due to compensation of donors by nitrogen acceptors. The electron concentrations ratio n(1×1015)/n(1×1016) decreases with increasing annealing temperature. Hall measurements showed that 1×1016 cm−2 N-implanted films became p-type after low temperature annealing in O2 at 200°C and in N2 at 400°C with hole concentrations of 3.2×1017 cm−3 and 1.6×1019 cm−3, respectively. Nitrogen-implanted ZnO:Ga films showed a c-axes preferred orientation of the crystallites. Annealing is shown to increase the average transmittance (>80%) of the films and to cause bandgap widening (3.19–3.3 eV).

Understanding the effects of growth conditions on the process of self-organisation of Ge nanostructures on Si is a key requirement for their practical applications. In this study we investigate the effect of preconditioning with a high-temperature hydrogenation step on the nucleation and subsequent temporal evolution of Ge self-assembled islands on Si (001). Two sets of structures, with and without H2 preconditioning, were grown by low pressure chemical vapour deposition (LPCVD) at 650°C. Their structural and compositional evolution was characterised by Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM) and micro-Raman (μRaman) spectroscopy. In the absence of preconditioning, we observe the known evolution of self-assembled Ge nanostructures on Si (001), from small islands with a narrow size distribution, to a bimodal size distribution, through to large islands. Surface coverage and island size increase steadily as a function of deposition time. On the H2 preconditioned surface, however, both nucleation rates and surface coverage are greatly increased during the early stages of self-assembly. After the first five seconds, the density of the islands is twice that on the unconditioned surface, and the mean island size is also larger, but the subsequent evolution is much slower than in the case of the unconditioned surface. This retardation correlates with a relatively high measured stress within the islands. Our results demonstrate that standard processes used during growth, like H2 preconditioning, can yield dramatic changes in the uniformity and distribution of Ge nanostructures self-assembled on Si. © 2004 Materials Research Society.

Doping of Ge with Sn atoms by ion implantation and annealing by solid phase epitaxial re-growth process was investigated as a possible way to create GeSn layers. Ion implantation was carried out at liquid nitrogen to avoid nano-void formation and three implant doses were tested: 5×10, 1×10 and 5×10 at/cm, respectively. Implant energy was set to 45 keV and implants were carried out through an 11 nm SiNO film to prevent Sn out-diffusion upon annealing. This was only partially effective. Samples were then annealed in inert atmosphere either at 350°C varying anneal time or for 100 s varying temperature from 300 to 500°C. SPER was effective to anneal damage without Sn diffusion at 350° for samples implanted at medium and low fluences whereas the 5×10 at/cm samples remained with a ∼15 nm amorphous layer even when applying the highest thermal budget. © 2012 American Institute of Physics.

The self-consistent Ion Beam Analysis (IBA) of cultural heritage samples using the external beam is technically demanding. We report on the calibration of an analysis of glass samples from the Rosslyn Chapel where the interest will ultimately be in the full characterisation of the weathered glass. Such an analysis requires a comprehensive Total-IBA approach using p-PIGE and He-PIXE to obtain ”bulk” and surface Na, with H-PIXE/EBS for multielemental depth profiling to 10 μm and He-PIXE/EBS for higher depth resolution near the surface; also with two PIXE detectors as usual for the high and low energy parts of the spectrum. A revised NDF v.10 code capable of a self-consistent handling of all these signals at state-of-the-art accuracy is described, together with the calibration protocols required for such an analysis. Other capabilities of the NDF code not previously discussed are also reviewed.

The fluorescence yield of the K- and L3-shell of gallium was determined using the radiometrically calibrated (reference-free) X-ray fluorescence instrumentation at the BESSY II synchrotron radiation facility. Simultaneous transmission and fluorescence signals from GaSe foils were obtained, resulting in K- and L3-shell fluorescence yield values (ωGa,K = 0.515 ± 0.019, ωGa,L3 = 0.013 ± 0.001) consistent with existing database values. For the first time, these standard combined uncertainties are obtained from a properly constructed Uncertainty Budget. These K-shell fluorescence yield values support Bambynek’s semi-empirical compilation from 1972: these and other measurements yield a combined recommended value of ωGa,K = 0.514 ± 0.010. Using the measured fluorescence yields together with production yields from reference Ga-implanted samples where the quantity of implanted Ga was determined at 1.3% traceable accuracy by Rutherford backscattering spectrometry, the K-shell and L3-subshell photoionization cross sections at selected incident photon energies were also determined and compared critically with the standard databases.

Code for extracting elemental depth profiles from IBA data, including Rutherford and non-Rutherford elastic scattering, nuclear reaction analysis, and particle induced X-ray emission. Designed for self-consistent fits of multiple spectra in large datasets. Validated by IAEA intercomparison, and many peer reviewed publications.

The suite of techniques which are available with the small accelerators used for MeV ion beam analysis (IBA) range from broad beams, microbeams or external beams using the various particle and photon spectrometries (including RBS, EBS, ERD, STIM, PIXE, PIGE, NRA and their variants), to tomography and secondary particle spectrometries like MeV-SIMS. These can potentially yield almost everything there is to know about the 3-D elemental composition of types of samples that have always been hard to analyse, given the sensitivity and the spacial resolution of the techniques used. Molecular and chemical information is available in principle with, respectively, MeV-SIMS and high resolution PIXE. However, these techniques separately give only partial information – the secret of “Total IBA” is to find synergies between techniques used simultaneously which efficiently give extra information. We here review how far “Total IBA” can be considered already a reality, and what further needs to be done to realise its full potential.

Surface modification of amorphous PET in incompatible blends is demonstrated using fluorocarbon end-functional polystyrenes. Contact angles with water and decane were consistent with high levels of surface fluorocarbon, even for spin-cast films with no further processing required. Hydrophobicity and lipophobicity were further increased by annealing above the glass transition temperature. High resolution depth profiling using complementary ion beam analysis and specular neutron reflectometry has enabled accurate characterisation of the composition profile of the additive including the minimum in additive concentration found just below the surface enriched layer. This analysis quantified the very low compatibility between the modifying polymer and the amorphous PET and was consistent with the highly segregated nature of the adsorbing species and its sharp interface with the subphase. For these incompatible polymer blends, surfaces enriched with the surface active polymer could coexist at equilibrium with extremely low (∼0.4%) bulk loadings of the additive. This suggests that for thicker films at even lower additive concentrations than the minimum 1% that we studied, it may be possible to achieve efficient surface modification. However, at this concentration, the efficiency of surface modification is limited by the processing conditions. Finally we note that in higher loadings of surface active additive there is clear evidence for lateral phase separation into patterned domains of differing composition. The enhancement in surface properties is due to local reorganisation rather than bulk redistribution of the components within the film, as the composition versus depth distributions of the polymer blend components was observed to be relatively unaffected by annealing.

The CdS window layer in thin film solar cells is frequently grown by chemical bath deposition (CBD). Deposited films are typically less than 100 nm thick and the inability to identify the exact start of the deposition can make CBD an imprecise process. This paper describes the construction and testing of a simple optical fibre sensor that detects the start of the deposition process and also allows for its mechanism to be studied. The in situ optical fibre monitoring technique utilises the change in optical reflectance off the glass/deposited film/precursor solution interfaces at an operating wavelength of 1550 nm. A theoretical expression for the reflection of light from the interface is discussed and compared with experimental results. The monitoring technique shows the presence of two different deposition mechanisms. This result is confirmed by film densities calculated by Rutherford backscattering spectrometry and an optical model for ellipsometry measurements which indicates that the deposited CdS films consist of a double layer structure with a porous layer on top of a dense under layer. The application of the theoretical expression is optimised by assuming the refractive index of the CdS layer to be 2.02. The ellipsometry model shows that the refractive index of the CdS deposited is 2.14 for a two layer model of the film that included a porous upper layer through the effective medium approximation.

The quantity of material in thin films can be measured reliably, non-destructively, and at an absolute traceable accuracy with a combined standard uncertainty of 1% by Rutherford backscattering spectrometry (RBS). We have demonstrated a measurement protocol for the determination of quantity of material by RBS that has been accredited at this accuracy to the ISO 17025 standard by the United Kingdom Accreditation Service (UKAS). The method is entirely traceable to SI units relying on no artefacts, and thus qualifies as a primary direct reference method as defined by the ISO Guide 35:1985 (paragraph 9.4.1).

Many disparate methods of compositional analysis of materials are underpinned by the same fundamental atomic processes: the excitation of the electronic system of the atoms followed by its subsequent relaxation. These methods include the electron spectroscopies (XPS, AES) used for surface studies, the electron microscopies used for elemental and structural characterisation (SEM using EDS and WDX; TEM using EELS), the X-ray methods (XRF, XAS) and ion beam analysis (PIXE) used for elemental and chemical characterisation. All rely on measuring the characteristic energy absorbed or emitted by the unknown target atom when its electronic system is excited by ionisation due to charged particles or electromagnetic radiation. This excitation is defined by the energy levels of the atomic electrons, determined primarily by the atomic number of the atom. (Atoms can also be excited without ionisation, as in optical and infra-red spectroscopy: this is outside the scope of this article.) The theoretical description of the electronic structure of atoms is a major intellectual triumph of the twentieth century and this body of knowledge is exploited in the theoretical description of each of these methods, but the treatment of any particular method is usually presented by specialists in that method in isolation from all others. In this chapter we present a brief synthetic overview of materials analysis using atomic excitation, highlighting those features and physical concepts which underpin all these apparently disparate analysis methods. We hope to encourage modern analysts to appreciate the truly complementary nature of the powerful methods at their disposal.

Ion beam analysis (IBA) includes modern analytical techniques involving the use of energetic ion beams to probe the composition of the surface layers of solids. Major areas of application include microelectronics, cultural heritage, forensics, biology and materials sciences. The underlying science for IBA is the physics of the interactions between the ions in the beam and the atoms in the solid. Emission products from the interaction of charged particles with matter are measured, and specialized simulation and data analysis software provide information on the material composition. Although the basic physical processes are well understood, the reliability of data interpretation is limited by the knowledge of the physical data. The primary quantities required are the stopping powers describing the slowing of the ion in the material and the cross-sections of the interactions involved. The need for reliable data on stopping powers is adequately catered for by Stopping and Range of Ions in Matter (SRIM) computer code. The situation, however, is quite different for cross-sections for nuclear reactions and non- Rutherford elastic scattering. Although there is a considerable body of published data in nuclear physics literature, examination of the unevaluated experimental data has revealed numerous discrepancies beyond the error limits reported by the authors. The lack of reliable cross-sections has been recognized by the IBA community and has been discussed at several workshops and IAEA meetings, resulting in various recommendations including the organization of a coordinated research project (CRP) on a reference database for IBA. The main objective of the CRP was to develop a reference database for IBA that contains reliable and usable data that will be made freely available to the user community. Starting from the existing collection of data in the IAEA Ion Beam Analysis Nuclear Data Library (IBANDL), the CRP focused exclusively on the relevant nuclear cross-sections (nuclear reactions and non-Rutherford elastic scattering). During the course of the CRP, however, it was soon realized that there was also a growing demand for compilation and evaluation of nuclear reactions with gamma rays in the exit channel, which are used in the particle induced gamma ray emission technique. The recommendations led to a second CRP on the development of a reference database for particle induced gamma ray emission spectroscopy. The output of which will be published in a forthcoming IAEA publication. The IAEA wishes to thank all the participants of the CRP for their contributions to IBANDL and to this publication. The IAEA officers responsible for this publication were D. Abriola and P. Dimitriou of the Division of Physical and Chemical Sciences.

A film of stoichiometric cadmium sulphide on quartz substrate was deposited by pyrolysis from bis-(morpholinodithioato-S,S') cadmium (C10H16N2O2S4Cd) (a single source precursor). The band gap of 2.4 eV was confirmed by optical absorption measurements. The stoichiometry and thickness were determined by Rutherford backscattering, and the absence of organic remmants in the film demonstrated by IR spectroscopy. © 1994.

Ion beam analysis (IBA) is a cluster of techniques including Rutherford and non-Rutherford backscattering spectrometry, and particle-induced X-ray emission (PIXE). Recently, the ability to treat multiple IBA techniques (including PIXE) self-consistently has been demonstrated. The utility of IBA for accurately depth profiling thin films is critically reviewed. As an important example of IBA, three laboratories have independently measured a silicon sample implanted with a fluence of nominally 5.1015As/cm2 at an unprecedented absolute accuracy. Using 1.5 MeV 4He+ Rutherford backscattering spectrometry (RBS), each lab has demonstrated a combined standard uncertainty around 1% (coverage factor k=1) traceable to an Sb-implanted certified reference material through the silicon electronic stopping power. The uncertainty budget shows that this accuracy is dominated by the knowledge of the electronic stopping, but that special care must also be taken to accurately determine the electronic gain of the detection system and other parameters. This RBS method is quite general and can be used routinely, to accurately validate ion implanter charge collection systems, to certify SIMS standards, and for other applications. The generality of application of such methods in IBA is emphasised: if RBS and PIXE data are analysed self-consistently then the resulting depth profile inherits the accuracy and depth resolution of RBS and the sensitivity and elemental discrimination of PIXE.

The nuclear matter and charge radii of the helium isotopes (A=4,6,8) are calculated by quantitative geometrical thermodynamics (QGT) taking as input the symmetry of the alpha-particle, the very weak binding (and hence halo nature) of the heavier helium isotopes, and a characteristic length scale given by the proton size. The results follow by considering each isotope in its ground state, with QGT representing each system as a maximum entropy configuration that conforms to the Holographic Principle. This allows key geometric parameters to be determined from the number of degrees of freedom available. QGT treats 6He as a 4He core plus a concentric neutron shell comprising a holomorphic pair of neutrons, and the 8He neutron halo is treated as a holomorphic pair of holomorphic pairs. Considering that the information content of each system allows a correlation angle of 2/3 between the holomorphic entities to be inferred, then the charge radii of the three isotopes can be calculated from the displacement of the 4He core from the centre of mass. The calculations for the charge and matter radii of 4,6,8He agree closely with observed values. Similar QGT calculation of the sizes of the self-conjugate A=4n nuclei {4He, 8Be, 12C, 16O, 20Ne, 24Mg, 28Si, 32S, 36Ar, 40Ca} also agree well with experiment.

Double-spiral galaxies are common in the Universe. It is known that the logarithmic double spiral is a Maximum Entropy geometry in hyperbolic (flat) spacetime that well represents an idealised spiral galaxy, with its central supermassive black hole (SMBH) entropy accounting for key galactic structural features including the stability and the double-armed geometry. Over time the central black hole must accrete mass, with the overall galactic entropy increasing: the galaxy is not at equilibrium. From the associated entropic Euler–Lagrange Equation (enabling the application of Noether’s theorem) we develop analytic expressions for the galactic entropy production of an idealised spiral galaxy showing that it is a conserved quantity, and we also derive an appropriate expression for its relativistic entropic Hamiltonian. We generalise Onsager’s celebrated expression for entropy production and demonstrate that galactic entropy production (entropy production corresponds to the intrinsic dissipation characteristics) is composed of two parts, one many orders of magnitude larger than the other: the smaller is comparable to the Hawking radiation of the central SMBH, while the other is comparable to the high entropy processes occurring within the accretion disks of real SMBHs. We conclude that galaxies cannot be isolated, since even idealised spiral galaxies intrinsically have a non-zero entropy production.

Techniques to analyze human telomeres are imperative in studying the molecular mechanism of aging and related diseases. Two important aspects of telomeres are their length in DNA base pairs (bps) and their biophysical nanometer dimensions. However, there are currently no techniques that can simultaneously measure these quantities in individual cell nuclei. Here, we develop and evaluate a telomere “dual” gold nanoparticle-fluorescent probe simultaneously compatible with both X-ray fluorescence (XRF) and super resolution microscopy. We used silver enhancement to independently visualize the spatial locations of gold nanoparticles inside the nuclei, comparing to a standard QFISH (quantitative fluorescence in situ hybridization) probe, and showed good specificity at ∼90%. For sensitivity, we calculated telomere length based on a DNA/gold binding ratio using XRF and compared to quantitative polymerase chain reaction (qPCR) measurements. The sensitivity was low (∼10%), probably because of steric interference prohibiting the relatively large 10 nm gold nanoparticles access to DNA space. We then measured the biophysical characteristics of individual telomeres using super resolution microscopy. Telomeres that have an average length of ∼10 kbps, have diameters ranging between ∼60–300 nm. Further, we treated cells with a telomere-shortening drug and showed there was a small but significant difference in telomere diameter in drug-treated vs control cells. We discuss our results in relation to the current debate surrounding telomere compaction.

Schlegel projections of selected fullerenes (the non-chiral C60, C384; and the weakly-chiral C28, C76 and C380) are used to show that these fullerenes can all be represented by pairs of counter-propagating spirals featuring anti-parallel (C2) symmetry, even though C380 and C384 are nonface-spiral fullerenes. In the case of C60, the high symmetry is used to construct an analytical approximation for these spirals, demonstrating that they form a holomorphic function satisfying the Euler-Lagrange equations, and thus confirming that the entropic equivalent of the Principle of Least Action (that is, the Principle of Least Exertion) is obeyed. Hence the C60 structure has Maximum Entropy (MaxEnt), is therefore maximum likelihood, and consequently its stability is established on entropic grounds. The present MaxEnt stability criterion is general, depending only on the geometry and not the physics of the system. A Shannon entropy-based fragmentation metric is used to quantify both the intrinsic sense and the degree of chirality for C76 and C380. We have shown that the stability of C60 is a general property of the thermodynamics of the system. This is a significant methodological advance since it shows that a detailed treatment of the energetics is not always necessary: this may prove fruitful, not only for fullerenes but also for general problems of molecular stability and in other applications of conformational chemistry.

A series of examples of increasing complexity is given of the unequivocal measurement of elemental depth profiles in thin films, typically with a depth resolution of 10 nm or better. The parameters of Fickian and related diffusion depth profiles can readily be obtained, reaction mechanisms under thermal annealing can be followed, layered structures can be characterised, and a robust statistical estimate of the solution uncertainties can be calculated. What is particularly interesting is that although individual IBA techniques (RBS, PIXE, etc) are powerful separately, using them together self-consistently - so-called "Total-IBA" is much more powerful, enabling the solution of complex systems inaccessible to individual techniques. There are now a number of Total-IBA examples in the literature and we choose two of them, one is the analysis by the Louvre Museum of corrosion in an iconic photograph from 1827 - one of their treasures - and the other an analysis of a geological sample 800,000 years old, from a meteor strike near Mount Darwin, Tasmania.

Beams of ions from electrostatic accelerators have long been used by curators, conservators, and archaeologists for deep analysis of the near-surface of cultural heritage samples after simpler methods have been exhausted. Ion beam analysis is a versatile and powerful method with many different imaging and analysis modalities which can be done without sample preparation and which is essentially nondestructive. This introduction is aimed at making users aware of the facilities available at national laboratories and how to use them, including a survey of characteristic and novel cultural heritage applications. The spectrometry modalities include particle-induced luminescence (both X-rays and optical photons), particle elastic and inelastic scattering, and combinations of these. Imaging at high spatial resolution is easy with modern equipment for all the spectrometries. These energetic particle beams are penetrating, allowing fully featured in-air analysis.

The truncated two-piece normal distribution is applied to data obtained from backscattering experiments in order to investigate the depth of arsenic implants in silicon.

When fabricating photonic crystals from suspensions in volatile liquids using the horizontal deposition method, the conventional approach is to evaporate slowly to increase the time for particles to settle in an ordered, periodic close-packed structure. Here, we show that the greatest ordering of 10 nm aqueous gold nanoparticles (AuNPs) in a template of larger spherical polymer particles (mean diameter of 338 nm) is achieved with very fast water evaporation rates obtained with near-infrared radiative heating. Fabrication of arrays over areas of a few cm2 takes only seven minutes. The assembly process requires that the evaporation rate is fast relative to the particles’ Brownian diffusion. Then a two-dimensional colloidal crystal forms at the falling surface, which acts as a sieve through which the AuNPs pass, according to our Langevin dynamics computer simulations. With sufficiently fast evaporation rates, we create a hybrid structure consisting of a two-dimensional AuNP nanoarray (or “nanogrid”) on top of a three-dimensional polymer opal. The process is simple, fast and one-step. The interplay between the optical response of the plasmonic Au nanoarray and the microstructuring of the photonic opal results in unusual optical spectra with two extinction peaks, which are analyzed via finite-difference time-domain method simulations. Comparison between experimental and modelling results reveals a strong interplay of plasmonic modes and collective photonic effects, including the formation of a high-order stop band and slow-light enhanced plasmonic absorption. The structures, and hence their optical signatures, are tuned by adjusting the evaporation rate via the infrared power density.

An experimental technique has been developed and applied to the problem of determining effective diffusion coefficients and partition coefficients of Sr in low permeability geological materials. This technique, the micro-reactor simulated channel method (MRSC), allows rapid determination of contaminant transport parameters with resulting values comparable to those determined by more traditional methods and also creates product surfaces that are amenable for direct chemical analysis. An attempt to further constrain mass flux was completed by detailed ion beam analysis of polished tuff surfaces (tuff is a polycrystalline polyminerallic aggregate dominated by silicate phases) that had been reacted with Sr solutions at concentrations of 10, 10 and 10 mol 1. Ion beam analysis was carried out using beams of both protons (using particle induced X-ray emission and elastic backscattering spectrometry or EBS) and alpha-particles (using Rutherford backscattering spectrometry). The ion beam analyses showed that increased solution concentrations resulted in increased surface concentrations and that in the highest concentration experiment, Sr penetrated to at least 4 mm below the primary interface. The Sr surface concentrations determined by EBS were 0.06 (±0.05), 0.87 (±0.30) and 2.40 (±1.0) atomic weight % in the experiments with starting solution concentrations of 10 , 10, and 10 mol 1, respectively. © 2012 The Mineralogical Society.

Rutherford back-scattering (RBS) and Medium Energy Ion Scattering (MEIS) have been used to determine the lattice site occupancy of antimony (Sb) implanted into silicon (Si) and strained silicon (sSi) for ion energies of 2keV to 40keV. After annealing in the range 600-1100°C for various times, Ilall effect measurements were used to provide a measure of the percentage electrical activity. A comparison of the lattice site occupancy with the percentage electrical activity was used to confirm whether the assumption that the Hall scattering factor is equal to unity is valid. Our results demonstrate that for 40keV implants the electrical activation is about 90%. In the case of 2keV implants the electrical activation is lower and in the range 10-80%, depending on the ion fluence and annealing conditions. This reduction in activation for lower energy implants is a result of inactive Sb close to the semiconductor/native-oxide interface, or above concentrations of 4.5×10cm . Tensile strain facilitates the lattice site occupancy and electrical activation of Sb in Si by raising the doping ceiling. For both 40keV and 2keV implants, we have carried out a comparison of RBS/MEIS and Hall effect data to show that for Sb implants into both bulk Si and strained Si the Hall scattering factor is equal to unity within experimental error.

We have calibrated on-site WD-XRF (wavelength-dispersive X-ray fluorescence) measurements of GeSbTe:N (GST:N) stoichiometry with off-site accurate ion beam analysis (IBA). N is determined by elastic backscattering spectrometry (EBS) using the resonance at 3.7 MeV in the 14N(a, a)14N reaction. Ge and Sb+Te are determined by Rutherford backscattering spectrometry (RBS) separately but self-consistently with the resonant EBS: the Sb/Te ratio can be determined by RBS but not with useful precision. The XRF instrumental function is determined using pure metal standards and the spectra are quantified using Fundamental Parameters code. We find that, as expected, for both Ge and (Sb+Te) the heavy elements are determined accurately by XRF (within the uncertainties), but for N the standardless XRF has non-linear errors around 10%. Using the absolute N content determined by IBA a calibration curve is obtained allowing N determination by WD-XRF at a precision of about 1% and an absolute accuracy (traceable through IBA) of about 4 % for GST films with N content between 4-20 at%. The IBA measurement precision of the N content of the GST-N XRF calibration samples is 0.4 at% (that is, a relative precision ranging from 10 % to 2 % for N contents between 4-20 at%).

The recent interest in germanium as an alternative channel material for PMOS has revealed major differences from silicon in relation to ion implantation. In this paper we describe some initial results of a fundamental study into defect creation and removal in ion implanted germanium. In this stage of the work we have used silicon and germanium implants into germanium and into germanium rich silicon-germanium. The defect evolution in these samples is compared with electron and neutron irradiated material using annealing studies in conjunction with deep level transient spectroscopy, positron annihilation and Rutherford back scattering. It is proposed that both vacancy and interstitial clustering are important mechanisms in implanted germanium and the likely significance of this is discussed. copyright The Electrochemical Society.

This is an abridgement of S.L.Jaki, "Science and Creation, from eternal cycles to an oscillating universe" (Scottish Academic Press, Edinburgh, 1974: 367pp, 14 chapters). Why is it that in all recorded history, modern science with all its technical success and mastery has arisen only in Europe? Science was stillborn in civilisations that thought of time as infinite in extent and cyclic in effect. Only in Europe, under the strong philosophical influence of Christianity, was time thought of as finite in extent and progressive in effect. The primary requirement for a scientific attitude to take hold is for there to be underlying presumptions that God is rational and that people matter. This essay attempts a summary of Stanley Jaki’s book, mostly in Jaki’s own words.

The analysis of thin films is of central importance for functional materials, including the very large and active field of nanomaterials. Quantitative elemental depth profiling is basic to analysis, and many techniques exist, but all have limitations and quantitation is always an issue. We here review recent significant advances in ion beam analysis (IBA) which now merit it a standard place in the analyst’s toolbox. Rutherford backscattering spectrometry (RBS) has been in use for half a century to obtain elemental depth profiles non-destructively from the first fraction of a micron from the surface of materials: more generally, “IBA” refers to the cluster of methods including elastic scattering (RBS; elastic recoil detection, ERD; and non-Rutherford elastic backscattering, EBS), nuclear reaction analysis (NRA), particle-induced X-ray emission (PIXE) and particle-induced gamma-ray emission (PIGE) which is a form of NRA. We have at last demonstrated what was long promised, that RBS can be used as a primary reference technique for the best traceable accuracy available for non-destructive model-free methods in thin films. Also, it has become clear over the last decade that we can effectively combine synergistically the quite different information available from the atomic (PIXE) and nuclear (RBS, EBS, ERD, NRA) methods. Although it is well known that RBS has severe limitations that curtail its usefulness for elemental depth profiling, these limitations are largely overcome when we make proper synergistic use of IBA methods. In this Tutorial Review we aim to briefly explain to analysts what IBA is and why it is now a general quantitative method of great power. Analysts have got used to the availability of the large synchrotron facilities for certain sorts of difficult problem, but there are many much more easily accessible mid-range IBA facilities also able to address (and often more quantitatively) a wide range of otherwise almost intractable thin film questions.

Understanding the effect of radiation damage and noble gas accommodation in potential ceramic hosts for plutonium disposition is necessary to evaluate their long-term behaviour during geological disposal. Polycrystalline samples of Nd-doped zirconolite and Nd-doped perovskite were irradiated ex situ with 2 MeV Kr+ at a dose of 5 1015 ions cm2 to simulate recoil of Pu nuclei during alpha decay. The feasibility of thin section preparation of both pristine and irradiated samples by Focused Ion Beam sectioning was demonstrated. After irradiation, the Nd-doped zirconolite revealed a well defined amorphous region separated from the pristine material by a thin (40–60 nm) damaged interface. The zirconolite lattice was lost in the damaged interface, but the fluorite sublattice was retained. The Nd-doped perovskite contained a defined irradiated layer composed of an amorphous region surrounded by damaged but still crystalline layers. The structural evolution of the damaged regions is consistent with a change from orthorhombic to cubic symmetry. In addition in Nd-doped perovskite, the amorphisation dose depended on crystallographic orientation and possibly sample configuration (thin section or bulk). Electron Energy Loss Spectroscopy revealed Ti remained in the 4+ oxidation state but there was a change in Ti coordination in both Nd-doped perovskite and Nd-doped zirconolite associated with the crystalline to amorphous transition.

The ubiquity of double helical and logarithmic spirals in nature is well observed, but no explanation is ever offered for their prevalence. DNA and the Milky Way galaxy are examples of such structures, whose geometric entropy we study using an information-theoretic (Shannon entropy) complex-vector analysis to calculate, respectively, the Gibbs free energy difference between B-DNA and P-DNA, and the galactic virial mass. Both of these analytic calculations (without any free parameters) are consistent with observation to within the experimental uncertainties. We define conjugate hyperbolic space and entropic momentum co-ordinates to describe these spiral structures in Minkowski space-time, enabling a consistent and holographic Hamiltonian-Lagrangian system that is completely isomorphic and complementary to that of conventional kinematics. Such double spirals therefore obey a maximum-entropy path-integral variational calculus (“the principle of least exertion”, entirely comparable to the principle of least action), thereby making them the most likely geometry (also with maximal structural stability) to be adopted by any such system in space-time. These simple analytical calculations are quantitative examples of the application of the Second Law of Thermodynamics as expressed in geometric entropy terms. They are underpinned by a comprehensive entropic action (“exertion”) principle based upon Boltzmann’s constant as the quantum of exertion.

Understanding the process of self-organization of Ge nanostructures on Si with controlled size distribution is a key requirement for their application to devices. In this study, we investigate the temporal evolution of self-assembled islands during the low pressure chemical vapour deposition (LPCVD) of Ge on Si at 650°C using high growth rates (6-9 nm/min). The islands were characterized by atomic force microscopy, transmission electron microscopy, Rutherford backscattering spectrometry and micro-Raman spectroscopy. We found that the first nanostructures to assemble were small islands, with a narrow size distribution, typical of the 'lens-shaped' structures reported in previous studies. Next to form were a population of larger 'lens-shaped' islands with a similar surface density to that of the small islands, but with broad height and width distributions. These islands differ from the pyramid-shaped islands previously reported for a similar size range. On further Ge deposition, the population evolves into one of large square-based truncated pyramids with a very narrow size distribution. Such pyramidal structures were previously reported at smaller sizes. Furthermore, we see no evidence of the multifaceted domes previously reported in this size range. The small 'lens-shaped' islands appear to be strained, whilst some of the intermediate-sized islands and all the large truncated pyramids contain misfit strain relaxation induced defects. Additionally, in the both the intermediate size 'lens-shaped' islands and in the large size truncated pyramidal islands, there is evidence of Si-Ge strain-induced alloying, more significant in the first than in the latter. Our observation of 'lens shaped' islands and truncated pyramids at larger sizes than are normally observed, suggests a kinetically driven process that delays the evolution of energetically favourable island structures until larger island sizes are reached.

Lateral ordered Co, Pt and Co/Pt nanostructures were fabricated in SiO2 and Si3N4 substrates by high fluence metal ion implantation through periodic nanochannel membrane masks based on anodic aluminium oxides (AAO). The quality of nanopatterning transfer defined by various AAO masks in different substrates was examined by transmission electron microscopy (TEM) in both imaging and spectroscopy modes.

The cell-to-cell variation of gold nanoparticle (GNP) uptake is important for therapeutic applications. We directly counted the GNPs in hundreds of individual cells, and showed that the large variation from cell-to-cell could be directly modelled by assuming log-normal distributions of both cell mass and GNP rate of uptake. This was true for GNPs non-specifically bound to fetal bovine serum or conjugated to a cell penetrating peptide. Within a population of cells, GNP content varied naturally by a factor greater than 10 between individual cells.

Both Rutherford backscatterings of He-4(+) beams and non-Rutherford backscatterings of He-4(+) and H+ beams have been used in this study to investigate the depth profiles of B dopant in Mg target upon B implantation and post annealing. Primitive data analysis suggests an enhanced diffusion of surface C contaminant during the B implantation process, together with enhanced surface oxidation upon implantation and thermal annealing in flowing N-2 atmosphere. Published by Elsevier B.V.

© 1990 IOP Publishing Ltd.High temperature, very short time annealing techniques have been used to study dopant activation during and immediately after solid phase epitaxial regrowth of amorphous layers produced by ion implantation of As into Si. Short annealing timescales have revealed electrically inactive As tails, correlated with a region of implant-induced excess point defects, indicating the formation of stable dopant-interstitial complexes which are not removed during the timescales of these anneals.

Return of materials from the Hubble Space Telescope (HST) during shuttle orbiter service missions has allowed inspection of large numbers of hypervelocity impact features from long exposure at about 615 km altitude in low Earth orbit (LEO) [1,2]. Here we describe the application of advanced X-ray microanalysis techniques on scanning electron microscopes (SEM), microprobes and a 2 MV Tandetron, to nearly 400 impacts on the painted metal surface of the Wide Field and Planetary Camera 2 (WFPC2) radiator shield [3,4]. We identified artificial Orbital Debris (OD) and natural Micrometeoroid (MM) origins for small [5] and even for larger particles [6], which usually may leave little or no detectable trace on HST solar arrays, as they penetrate through the full cell thickness [2,7].

Ion beam techniques are used with ion energies from eV to many MeV and a very wide range of ion species to characterise materials at length scales from sub-nm to sub-mm and in a wide variety of different ways. Many of these techniques are non destructive. Atomic concentration can be determined from matrix elements (the stoichiometry) to minor and trace elements (at ng/g sensitivity and better), in one dimension (depth profiles), two dimensions (elemental maps), and three dimensions with full tomography being feasible. There is sensitivity to the whole Periodic Table one way or another, with nuclear techniques for isotopic sensitivity, and high resolution mass spectrometry for obtaining isotopic ratios at ultra-high sensitivities of 1014 and better. Other techniques include ultra-high resolution microscopy, characterisation of semiconductor device defects at high spacial resolution, and the investigation of damage processes in the nuclear irradiation of materials. ION BEAM METHODS for thin film materials have major application areas from archaeology to zoology (including materials science, geology, cultural heritage, electronics and many others).

We have introduced defects into clean samples of the organic superconductor -BEDTTTF 2CuSCN2 in order to determine their effect on the temperature dependence of the interlayer conductivity and the critical temperature Tc. We find a violation of Matthiessen’s rule that can be explained by a model of involving a defect-assisted interlayer channel which acts in parallel with the bandlike conductivity. We observe an unusual dependence of Tc on residual resistivity, inconsistent with the generalized Abrikosov-Gor’kov theory for an order parameter with a single component, providing an important constraint on models of the superconductivity in this material.

Reactive ion etching (RIE) of p-type 2-3 Ωcm resistivity silicon (100) was characterized using Photoreflectance (PR), Rutherford Backscattering Spectrometry (RBS) and Spectroscopic Ellipsometry (SE). Isochronal (5 minutes) etching was performed at various DC etch biases (0-500 V) using a SiCl4 etch chemistry. The substrate etch rate dependence on applied bias was determined using mechanical profilometry. A distinct shift in the Λ3-Λ1 Si transition and significant spectral broadening of the room temperature PR spectra was observed as a function of etch bias. Photoreflectance results are correlated with RBS, SE and etch rate analysis. It is demonstrated that the PR spectra reflect a complex, competitive, plasma-surface interaction during the RIE process.

© 1989 Springer-Verlag Heidelberg. © 1989 Springer-Verlag Bcrbn Heidelberg. All Rights Reserved.This paper correlates photodisplacement thermal wave characterization of ion implanted silicon wafers with the lattice information provided by Rutherford Backscattering Spectrometry.

Radiation detectors for medical imaging at room temperature have been developed thanks to the availability of large chlorine-compensated cadmium telluride (CdTe:Cl) crystals. Microstructural defects affect the performance of CdTe:Cl radiation detectors. Advanced characterization tools, such as Ion Beam Induced Current (IBIC) measurements and chemical etching on tellurium and cadmium faces were used to evaluate the influence of sub-grain-boundaries on charge carrier transport properties. We performed IBIC imaging to correlate inhomogeneities in charge collection for both types of charge carrier with distribution of dislocation walls in the sample. This information should help improve performance in medical imaging applications. © 2013 Elsevier B.V.

Silicon carbide (SiC) is a superior material potentially replacing conventional silicon for high-power and high-frequency microelectronic applications. Ion beam synthesis (IBS) is a novel technique to produce large-area, high-quality and ready-to-use SiC crystals. The technique uses high-fluence carbon ion implantation in silicon wafers at elevated temperatures, followed by high-energy heavy ion beam annealing. This work focuses on studying effects from the ion beam annealing on crystallization of SiC from implanted carbon and matrix silicon. In the ion beam annealing experiments, heavy ion beams of iodine and xenon, the neighbors in the periodic table, with different energies to different fluences, I ions at 10, 20, and 30MeV with 1-5×10 12ions/cm 2, while Xe ions at 4MeV with 5×10 13 and 1×10 14ions/cm 2, bombarded C-ion in implanted Si at elevated temperatures. X-ray diffraction, Raman scattering, infrared spectroscopy were used to characterize the formation of SiC. Non-Rutherford backscattering and Rutherford backscattering spectrometry were used to analyze changes in the carbon depth profiles. The results from this study were compared with those previously reported in similar studies. The comparison showed that ion beam annealing could indeed induce crystallization of SiC, mainly depending on the single ion energy but not on the deposited areal density of the ion beam energy (the product of the ion energy and the fluence). The results demonstrate from an aspect that the electronic stopping plays the key role in the annealing.

Darwin glass is an impact glass resulting from the melting of local rocks during the meteorite impact that formed the 1.2 km diameter Darwin Crater in western Tasmania. These glass samples have small spheroidal inclusions, typically a few tens of microns in diameter, that are of great interest to the geologists. We have analysed one such inclusion in detail with proton microbeam ion beam analysis (IBA). A highly heterogeneous composition is observed, both laterally and in depth, by using self-consistent fitting of photon emission and particle backscattering spectra. With various proton energies near 2 MeV we excite the C-12(p,p)C-12 resonance at 1734 keV at various depths, and thus we can probe both the C concentration, and also the energy straggling of the proton beam as a function of depth which gives information on the sample structure. This inclusion has an average composition of (C, O, Si) = (28, 56, 16) mol% with S, K, Ca, Ti and Fe as minor elements and Cr, Mn, Ni, Cu, Zn and Br as trace elements. This composition includes, at specific points, an elemental depth profile and a density variation with depth consistent with discrete quartz crystals a few microns in size. (c) 2009 Elsevier B.V. All rights reserved.

There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically.