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Characterizing proton beam damage in biological materials is of interest to enable the integration of proton microprobe elemental mapping techniques with other imaging modalities. It is also of relevance to obtain a deeper understanding of mechanical damage to lipids in tissues during proton beam cancer therapy. We have developed a novel strategy to characterize proton beam damage to lipids in biological tissues based on mass spectrometry imaging. This methodology is applied to characterize changes to lipids in tissues ex vivo, irradiated under different conditions designed to mitigate beam damage. This work shows that performing proton beam irradiation at ambient pressure, as well as including the application of an organic matrix prior to irradiation, can reduce damage to lipids in tissues. We also discovered that, irrespective of proton beam irradiation, placing a sample in a vacuum prior to desorption electrospray ionization imaging can enhance lipid signals, a conclusion that may be of future benefit to the mass spectrometry imaging community.

Elemental imaging is widely used for imaging cells and tissues but rarely in combination with organic mass spectrometry, which can be used to profile lipids and measure drug concentrations. Here, we demonstrate how elemental imaging and a new method for spatially resolved lipidomics (DAPNe-LC-MS, based on capillary microsampling and liquid chromatography mass spectrometry) can be used in combination to probe the relationship between metals, drugs, and lipids in discrete areas of tissues. This new method for spatial lipidomics, reported here for the first time, has been applied to rabbit lung tissues containing a lesion (caseous granuloma) caused by tuberculosis infection. We demonstrate how elemental imaging with spatially resolved lipidomics can be used to probe the association between ion accumulation and lipid profiles and verify local drug distribution.

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.

Elemental and molecular imaging play a crucial role in understanding disease pathogenesis. To accurately correlate elemental and molecular markers, it is desirable to perform sequential elemental and molecular imaging on a single-tissue section. However, very little is known about the impact of performing these measurements in sequence. In this work, we highlight some of the challenges and successes associated with performing elemental mapping in sequence with mass spectrometry imaging. Specifically, the feasibility of molecular mapping using the mass spectrometry imaging (MSI) techniques matrix-assisted laser desorption ionization (MALDI) and desorption electrospray ionization (DESI) in sequence with the elemental mapping technique particle-induced X-ray emission (PIXE) is explored. Challenges for integration include substrate compatibility, as well as delocalization and spectral changes. We demonstrate that while sequential imaging comes with some compromises, sequential DESI-PIXE imaging is sufficient to correlate sulfur, iron, and lipid markers in a single tissue section at the 50 μm scale.

Ion Beam Analysis (IBA) consists of a set of analytical techniques addressing elemental composition of inorganic material normally conducted using ion beams in the MeV kinetic energy range. Secondary Ion Mass Spectrometry using MeV ions (MeV SIMS) is the only IBA technique which can provide extensive molecular information about organic materials. MeV ions can be extracted into air hence offering the potential to apply MeV SIMS under atmospheric pressure. At the University of Surrey Ion Beam Centre, a fully ambient MeV SIMS setup has been developed and termed “Ambient Pressure MeV SIMS”. This AP MeV SIMS can be optimized for analysis and imaging of organic molecules. MeV SIMS relies upon electronic sputtering of the target material and this is much more efficient in insulating or organic targets, and less efficient in conducting metallic materials. PIXE, on the other hand, is efficient at providing good signals from elemental metallic systems, but does not readily provide molecular information from organics. The combination of the two techniques – preferably simultaneously with the same beam – provides useful complementary information which can readily be combined. Here we present pioneering preliminary work in simultaneous molecular and elemental imaging of a complex sample comprising of two organic species and two metallic species by combining AP MeV SIMS with Heavy Ion Particle Induced X-ray emission (HIPIXE).

Ambient Pressure MeV SIMS (AP MeV SIMS) is a special application of MeV SIMS technique for molecular detection and imaging under ambient conditions. There are several advantages of using ambient over nonambient techniques such as minimising or completely avoiding sample preparation that can contribute to the reducing of costs and shortening of analysis. Moreover, by performing analysis in ambient conditions negative vacuum influence on samples will be avoided. The emergence of ambient mass spectrometry techniques over the past decade has been enormous with a broad range of applications such as food quality, environmental analysis and life sciences [1,2]. On the other hand, the disadvantage of ambient pressure mass spectrometry techniques is the influence of the ambient background which can suppress the signal from the target. In AP MeV SIMS, molecular species present in ambient surrounding of the sampling site will also be ionised by ion beams hence secondary ions originating from the sample have to be transported in the most efficient manner from the site of interaction of ion beams and target into the mass spectrometer capillary and, finally, into the mass spectrometer [3]. In this work, we present the optimisation of the mass spectrometer capillary temperature, distances of mass spectrometer and sheath gas, in our case helium, with respect to the beam axis and angle of the helium flow capillary with respect to the sample.

In this publication we work towards providing fast, sensitive and selective analysis of explosive compounds collected on swabs using paper spray mass spectrometry. We have (a) increased the size of the paper spray substrate to 1.6×2.1 cm for compatibility with current practise in swabbing for explosive material; (b) developed a method for determining a successful extraction of analyte from the substrate to reduce false negative events; and (c) expanded the range of analytes that can be detected using paper spray to include the peroxide explosive HMTD, as well as nitroglycerine (NG), picric acid (PA) and tetryl. We report the development of a 30 s method for the simultaneous detection of 7 different explosive materials using PSMS with detection limits below 25 pg, as well as detection of HMTD at 2500 pg, showing an improvement on previously published work.

We demonstrate that the simultaneous combination of ion beam analysis (IBA) and ion beam induced luminescence (IL) can reveal valuable information concerning the performance of strained doped silica fibre thermoluminescence microdosimeters. The micron scale spatial resolution and low detection limits of IBA allow the lateral distribution of dopant elements to be mapped and then correlated with the distribution of prompt radioluminescence. Measurement of the decay of the IL signal with dose provide information concerning the saturation of the subsequent TL signal at high doses. MeV ion beams can deposit relatively high energy in localized, well-quantified small volumes and so this method is valuable for studying high dose effects in TL dosimeters. We describe a simple modification of the target chamber microscope which enables sensitive low background light detection in two wavelength bands and present preliminary results from three types of germanium doped silica fibre dosimeter.

“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.

Direct analyte probed nanoextraction (DAPNe) is a technique that allows extraction of drug and endogenous compounds from a discrete location on a tissue sample using a nano capillary filled with solvent. Samples can be extracted from a spot diameters as low as 6 µm. Studies previously undertaken by our group have shown that the technique can provide good precision (5%) for analysing drug molecules in 150 µm diameter areas of homogenised tissue, provided an internal standard is sprayed on to the tissue prior to analysis. However, without an isotopically labelled standard, the repeatability is poor, even after normalisation to and the spot area or matrix compounds. By application to tissue homogenates spiked with drug compounds, we can demonstrate that it is possible to significantly improve the repeatability of the technique by incorporating a liquid chromatography separation step. Liquid chromatography is a technique for separating compounds prior to mass spectrometry (LC-MS) which enables separation of isomeric compounds that cannot be discriminated using mass spectrometry alone, as well as reducing matrix interferences. Conventionally, LC-MS is carried out on bulk or homogenised samples, which means analysis is essentially an average of the sample and does not take into account discrete areas. This work opens a new opportunity for spatially resolved liquid chromatography mass spectrometry with precision better than 20%.

RATIONALE: Paper spray offers a rapid screening test without the need for sample preparation. The incomplete extraction of paper spray allows for further testing using more robust, selective and sensitive techniques such as liquid chromatography mass spectrometry (LC-MS). Here we develop a two-step process of paper spray followed by LC-MS to (1) rapidly screen a large number of samples and (2) confirm any disputed results. This demonstrates the applicability for testing medication adherence from a fingerprint. METHODS: Following paper spray analysis, drugs of abuse samples were analysed using LC-MS. All analyses were completed using a Q Exactive™ Plus Orbitrap™ mass spectrometer. This two-step procedure was applied to fingerprints collected from patients on a maintained dose of the antipsychotic drug quetiapine. RESULTS: The extraction efficiency of paper spray for two drugs of abuse and metabolites was found to be between 15-35% (analyte dependent). For short acquisition times, the extraction efficiency was found to vary between replicates by less than 30%, enabling subsequent analysis by LC-MS. This two-step process was then applied to fingerprints collected from two patients taking the antipsychotic drug quetiapine, which demonstrates how a negative screening result from paper spray can be resolved using LC-MS. CONCLUSIONS: We have shown for the first time the sequential analysis of the same sample using paper spray and LC-MS, as well as the detection of an antipsychotic drug from a fingerprint. We propose that this workflow may also be applied to any type of sample compatible with paper spray, and will be especially convenient where only one sample is available for analysis.

Paper spray mass spectrometry is a rapid and sensitive tool for explosives detection but has so far only been demonstrated using high resolution mass spectrometry, which bears too high a cost for many practical applications. Here we explore the potential for paper spray to be implemented in field applications with portable mass spectrometry. This involved (a) replacing the paper substrate with a swabbing material (which we call “swab spray”) for compatibility with standard collection materials; (b) collection of explosives from surfaces; (c) an exploration of interferences within a ± 0.5 m/z window; and (d) demonstration of the use of high-field assisted waveform ion mobility spectrometer (FAIMS) for enhanced selectivity. We show that paper and Nomex® are viable collection materials, with Nomex providing cleaner spectra and therefore greater potential for integration with portable mass spectrometers. We show that sensitive detection using swab spray will require a mass spectrometer with a mass resolving power of 4000 or more. We show that by coupling the swab spray ionisation source with FAIMS, it is possible to reduce background interferences, thereby facilitating the use of a low resolving power (e.g. quadrupole) mass spectrometer. Keywords: Explosives, Swab spray, Mass spectrometry, FAIMS

The material characteristics of doped SiO2 fibre are studied, the electron traps in the product medium creating a situation attractive for their application in thermoluminescence (TL) radiation dosimetry. To date, rather limited research has been conducted towards gaining an essential understanding of the magnitude of TL signal and material characteristics of doped fibres. Characterization is being sought to ensure that the mechanism of TL yield in optical fibres is well understood, allowing a favourable well controlled production situation to be established. The intended end point is to specify dosimeters, not only for clinical dosimetry but also for their application in industrial/energy–industry settings. Investigation of the surface oxidation state of the Ge-doped SiO2 optical preform has been carried out using the X-ray photoelectron spectroscopy technique. In a further development using the fibre forming technology, particle-induced X-ray emission/Rutherford back scattering measurements have been employed to ascertain dopant concentrations of Ge-doped-cladding photonic crystal fibres (PCFs) with a view to improving TL yield. Present results concern uncollapsed and collapsed-hole-PCFs.

The proton beam writing (PBW) technique was used to fabricate microfluidic structures in SU-8 resist. A network of the buried channels was fabricated as part of a project to develop functional microfluidic device for neuronal studies and self-powered microfluidics. Protons with energies between 2.5 MeV and 0.75 MeV were used to fabricate the buried channels with a minimum feature size of around 1 μm and depths of 40–55 μm. Roughness of channels sidewalls was around 2.5 nm rms. Exposure regime and examples of functional networks fabricated using PBW are described. COMSOL Multiphysics® software was used to model the flow characteristics of fluid in the SU-8 microchannels structured by PBW. The results obtained using PBW are compared with the structures fabricated by UV-lithography.

The Surrey Ion Beam Centre was awarded the Engineering and Physical Sciences Research Council (EPSRC) grant for “Promoting Cross Disciplinary Research: Engineering and Physical Sciences and Social Sciences” allowing continued research into the characteristics of desorption of secondary ions by the impact of fast primary ions in the ambient pressure at the sub-micron scale. To carry out this research a new beamline has been constructed consisting of a time-of-flight secondary ion mass spectrometer combined with the current 2MV Tandem accelerator. This research has already returned many significant results such as the first simultaneous SIMS, PIXE and RBS measurement preformed on an organic sample in vacuum. However, further optimization and validation of the new beamline is still being worked on. This work focuses on the optimization of the end station geometry to allow for high sensitivity ambient pressure measurements. It is concluded that a common geometry can be adopted for a wide variety of smooth samples to ensure optimum sensitivity provided a hard edge of the sample can be found to place the mass spectrometer capillary near.

Sample elemental concentrations can be determined using the microbeam proton-induced X-ray emission (PIXE) technique, providing non-destructive simultaneous low-background multi-element analysis. Present interest concerns analysis of Ge-doped SiO2 fibres intended as high spatial-resolution thermoluminescence (TL) dosimeters for radiation measurements in place of their more typical applications in telecommunications. During fibres fabrication, defined amounts of the Ge dopant are added, the dopant more usually having a determining role in the transmission properties of the fibre. Characteristic X-rays produced in PIXE analysis provide information on the relative distribution of elements within a sample, as in for instance Ge and Si concentrations, the Ge acting as point defect centres that promote TL. With the dopant tending to diffuse in and away from the fibre core, it is essential to define the sample matrix composition in order to accurately evaluate the X-ray yield. This is determined in part using simultaneous Rutherford Back Scattering analysis. In present work, PIXE/Rutherford Back Scattering measurements have been employed to ascertain dopant concentrations of fibres that have been fabricated at the University of Malaya with a view to improving TL yield. Present results concern cylindrical fibres, nominally with 4%, 6% and 8% weight peak Ge concentrations and flat fibres of nominal 6% weight Ge concentration. For the cylindrical fibres, Ge dopant concentration has been found to be in the range of 2.41–4.56%, 6.44–8.29% and 10.27–12.25% weight, respectively, while for the flat fibres, the Ge concentration range is broader, at 0.07–6.55% weight. Copyright © 2014 John Wiley & Sons, Ltd.

BACKGROUND Paper spray mass spectrometry (PS-MS) is a technique that has recently emerged and has shown excellent analytical sensitivity to a number of drugs in blood. As an alternative to blood, fingerprints have been shown to provide a noninvasive and traceable sampling matrix. Our goal was to validate the use of fingerprint samples to detect cocaine use. METHODS Samples were collected on triangular pieces (168 mm2) of washed Whatman Grade I chromatography paper. Following application of internal standard, spray solvent and a voltage were applied to the paper before mass spectrometry detection. A fingerprint visualization step was incorporated into the analysis procedure by addition of silver nitrate solution and exposing the sample to ultraviolet light. RESULTS Limits of detection for cocaine, benzoylecgonine, and methylecgonine were 1, 2, and 31 ng/mL respectively, with relative standard deviations < 33%. No matrix effects were observed. Analysis of 239 fingerprint samples yielded a 99% true-positive rate and a 2.5% false-positive rate, based on the detection of cocaine, benzoylecgonine, or methylecgonine with use of a single fingerprint. CONCLUSIONS The method offers a qualitative and noninvasive screening test for cocaine use. The analysis method developed is rapid (4 min/sample) and requires no sample preparation.

The quality of the structures fabricated using proton beam writing (PBW) and other direct-write microfabrication methods is strongly influenced by the path followed by the writing beam during the exposure. In particular, it is necessary to avoid paths in which the beam makes large jumps or changes in direction close to the edges of the structure, and ideally the scan path should follow the outline of the pattern to be exposed (sometimes referred to as turtle scanning). While this is relatively easy to implement when the patterns to be created can be built up from simple geometric shapes (circles, rectangles, etc), it has not been possible to do this in the case of arbitrarily complex images, at least using software available to the PBW community. This paper describes a simple edge-following algorithm (EFA) which uses a method of spiral searching around each pixel to determine a scan path which not only optimizes the conformity of the scan path to the edges of the required pattern, but also minimizes jumps (and hence blanking time) and scan reversals which can cause artefacts due to scanning system transients. The EFA operates on a 1-bit BMP format input image file and has been implemented in the OMDAQ-3 software package (Oxford Microbeams Ltd). The paper is illustrated with examples of complex structures written using the EFA at the University of Surrey Ion Beam Centre which demonstrate enhanced edge smoothness compared with simple blanked raster scanning.

A "broadbeam" facility is demonstrated for the vertical microbeam at Surrey's Ion Beam Centre, validating the new technique used by Barazzuol et al. (Radiat Res 177:651-662, 2012). Here, droplets with a diameter of about 4 mm of 15,000 mammalian cells in suspension were pipetted onto defined locations on a 42-mm-diameter cell dish with each droplet individually irradiated in "broadbeam" mode with 2 MeV protons and 4 MeV alpha particles and assayed for clonogenicity. This method enables multiple experimental data points to be rapidly collected from the same cell dish. Initially, the Surrey vertical beamline was designed for the targeted irradiation of single cells with single counted ions. Here, the benefits of both targeted single-cell and broadbeam irradiations being available at the same facility are discussed: in particular, high-throughput cell irradiation experiments can be conducted on the same system as time-intensive focused-beam experiments with the added benefits of fluorescent microscopy, cell recognition and time-lapse capabilities. The limitations of the system based on a 2 MV tandem accelerator are also discussed, including the uncertainties associated with particle Poisson counting statistics, spread of linear energy transfer in the nucleus and a timed dose delivery. These uncertainties are calculated with Monte Carlo methods. An analysis of how this uncertainty affects relative biological effect measurements is made and discussed. © 2013 Springer-Verlag Berlin Heidelberg.

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.

The Surrey Ion Beam Centre (IBC) is routinely using focused MeV primary ions to generate two-dimensional molecular maps using time-of-flight secondary ion mass spectrometry (ToF-SIMS) collected simultaneously with particle induced X-ray emission (PIXE) and Rutherford backscattering (RBS) spectra. Measurements made with the ToF-SIMS, PIXE, and RBS device with a focused and scanned MeV primary ion beam provide a more complete elemental and molecular evaluation of the target sample’s surface. In this paper, we explore the use of high electronic energy loss by MeV primary ions in the surface region of the target as a method for generating molecular images of the surface. We provide analyses of the relative secondary ion yield of leucine molecules as a function of primary ion velocity using MeV primary ions. We also demonstrate our ability to collect PIXE, RBS, and ToF-SIMS images generated using the same MeV primary ion.

This paper evaluates the lens aberrations in microbeam and nanobeam systems caused by stray DC magnetic fields. Stray DC fields are far less influential on focussed beam spots than stray AC fields, but in order to achieve good beam-spot resolution the beamline must be aligned to the stray DC fields in the laboratory. The relative thickness of the optical elements compared to the curvature of the beam in such fields causes aberration where the beam axis differs from the optical axis of the lens system. In this paper numerical ray tracing has been used to study the influence of stray DC magnetic fields on beam resolution at the sub-micron level using typical field strengths for the Earth’s magnetic field as a case study.

Recent results [1] show the potential of using monomer primary ions accelerated to several MeV with a tandem accelerator to achieve the necessary secondary ion yields to image large (above 1 kDa) molecules with submicron lateral resolutions. The Surrey ion Beam Centre (Surrey IBC) has designed a time-of-flight secondary ion mass spectrometer (ToF-SIMS) combined with a 2 MV Tandem accelerator to investigate the characteristics of the desorption of secondary ions by the impact of fast, heavy, primary ions. The application of this MeV-ToF-SIMS technique is intended to eventually image biomolecules in the subcellular regime without the need for matrix application associated with other mass spectromery techniques, such as Matrix Assisted Laser Desorption ionisation (MALDI). A discussion is given to point out the merits of using a combination of Particle-Induced X-ray Emission Spectrometry (PIXE) and Rutherford Backscattering (RBS) with the MeV-ToF-SIMS measurement to improve quantification and sensitivity of this surface analysis technique. We also present data from highly focused MeV primary ions to directly compare results obtained using keV cluster-SIMS to measure various biological materials using ToF-SIMS through sputtering in both the nuclear and electronic stopping regimes. Our findings show that the mass spectra obtained with MeV ions in the electronic stopping regime show similarities to those acquired with more conventional keV ion beams (e.g. Bi + , Bi 3 + , Bi 5 + and C 60 + ). MeV-ToF-SIMS has the potential for becoming a widely used quantitative surface analysis technique in the many ion beam analysis facilities already conducting-high energy ion beam analyses.

Ultra low energy SIMS (uleSIMS) is a high sensitivity analytical technique that is normally used for ultra shallow profiling at a depth resolution of up to1 nm. This work describes the use of uleSIMS as both a spectroscopic and depth-profiling tool for the characterization of the early stages of corrosion formed on reference surfaces of silver. These samples are being developed to help with the characterization of tarnished surfaces in a cultural heritage context, and uleSIMS enables the tarnishing to be studied from its very earliest stages due to its high sensitivity (ppm–ppb) and surface specificity. We show that, uleSIMS can be used effectively to study the surface chemistry and aid the development of reference surfaces themselves. In particular, handling contaminants, surface dust, and residues from polishing are relatively easy to identify allowing them to be separated from the parts of the mass spectrum specific to the early stages of corrosion.

A simple design for a caesium sputter cluster ion source compatible with commercially available secondary ion mass spectrometers is reported. This source has been tested with the Cameca IMS 4f instrument using the cluster Si-n(-) and Cu-n(-) ions, and will shortly be retrofitted to the floating low energy ion gun (FLIG) of the type used on the Cameca 4500/4550 quadruple instruments. Our experiments with surface characterization and depth profiling conducted to date demonstrate improvements of analytical capabilities of the SIMS instrument due to the non-additive enhancement of secondary ion emission and shorter ion ranges of polyatomic projectiles compared to atomic ions with the same impact energy. (c) 2006 Elsevier B.V. All rights reserved.

This paper describes a new application in cultural heritage and other areas for a highly surface specific analytical technique originally developed for semiconductor research. The technique, ultra-low-energy dynamic secondary ion mass spectrometry (uleSIMS), is microdestructive, but has a sensitivity typically better than 1 atom in 106. It can provide an analysis within the top nm, or the top few μm of a surface, and gives chemical fingerprinting as well as atomic composition information. It is complimentary to other near-surface techniques such as SEM-EDX, XRD and electrochemical methods. Here, we describe the use of uleSIMS with SEM and SEM-EDX in a study of the tarnishing of museum silver. We report on the initial stages in the development of reference surfaces for control experiments, and on the data obtained from a lightly tarnished sterling silver test coupon exposed in a museum environment for 2 years. First results from a study of a XVII c. silver fragment, aimed at detecting differences in the tarnish or coating in different areas are also presented. Overall we show that the surface chemistry of all these surfaces is a complex mixture of that due to corrosion, contaminants deposited by solvents, polish media (in an overlayer which may only be a few nm thick), handling and the environment, as well as particulates – both from the environment and from polishes. However, surfaces with different histories show large variations in their uleSIMS spectra and depth profiles, and we attempt to lay the groundwork for the interpretation of these.

The primary beam energy and species (Cs + , Ar + ) dependence of ultra low energy SIMS depth profiles of ultra-shallow boron implants into CVD grown diamond is investigated in this paper. The data are compared with TRIM simulation of the 5 keV 11 B + implant. Cs + profiles (1 keV, 30°) appear to be seriously distorted by atomic mixing and recoil implantation due to the high mass of the probe. Ar + profiles (300 eV-1 keV, 0°) are less distorted, but both Cs + and Ar + tend to produce significant tails. The Ar + SIMS profiles produce implants which appear to be shallower than the TRIM simulation. We show that profiling using Ar + with energies between 0.3 and 1 keV can be used to extrapolate a profile to zero beam energy. The extrapolated data indicate a centroid between 5 and 10 nm from the surface, whereas TRIM predicts 11 nm.

Experiments are reported on the non-additivity of a multiply charged ion emission with various atomic and molecular projectiles. A distinction has been found in the non-additivity of the Si2+ emission from Si. It manifests itself as a change of the non-additivity factor K2,1 from K2,1 1 (non-additive enhancement effect) in going from Au2− to Cu2− projectiles. It was shown that the sub-linear behaviour of K2,1 is caused by the correlated move of projectiles gold atoms in a target matter (the clearing-the-way effect) and the origin of the non-additive enhancement is not determined by non-linear cascade sputtering. On the basis of the results obtained a new effect in an ion-induced atomic-like Auger electron emission has been predicted.

One of the fundamental limitations in the performance of MeV ion microbeam focusing systems is the effect of ion scattering at the edges of the object aperture. As the aperture is reduced in the search for smaller spot sizes, the fraction of scattered to unscattered beam increases. The scattered beam contains lower energy particles which can be transmitted through the system to create a halo of over-focused particles surrounding the final image. Removal of this halo is critical to achieving small spot sizes, especially in single ion applications. In this paper, we discuss the use of a Wien filter (crossed magnetic and electrostatic fields) to deflect the reduced energy scattered particles and ensure that only ions with the correct energy are accepted into the lens. This paper reviews the beam optics of Wien filter systems and presents calculations of the parameters required to obtain useful energy dispersion.

The development of an ambient pressure MeV SIMS ion beam analysis capability at the Surrey Ion Beam Centre has necessitated the development of a system to protect the vacuum integrity of the main 2 MV tandem particle accelerator. The development and operating characteristics of a fast acting vacuum isolation valve based on the principle of an induction coil are reported and shown to be suitable for the intended application.

Temperature dependencies have been measured within a wide range of target temperatures of 300 K ≤ T ≤ 2400 K for secondary ion yields of Tan+, TanOm+, TanNb+ and TanAu+ (n = 1–14, m = 1–3) under the bombardment of tantalum target with 12 keV atomic Au− and 18 keV polyatomic Au3− projectiles. It is demonstrated that yields of Tan+ (n = 2–14) and TanNb+ ions increase with temperature for T ≤ 1700 K and then tend to become temperature independent. On the contrary, the yields of TanOm+ and TanAu+ ions slightly increase with temperature reaching their maxima in the range of 1000 K ≤ T ≤ 1500 K and then sharply decrease to zero at T ≈ 1700 and 2100 K, respectively. These trends are interpreted to indicate the redistribution of the sputtered flux between these different emission channels while sputtering conditions change with the target temperature. Oxygen presence on the surface at lower temperatures limits the yield of Tan+ clusters and stimulates that of TanOm+. Removing oxygen from the surface enhances the yield of Tan+ clusters and the disappearance of TanOm+. After clean surfaces are established in the range of 1700 K ≤ T ≤ 2400 K, the yield of the Tan+ and TanNb+ cluster ions becomes constant thus indicating that their ionization probability does not depend on the target temperature in this range. Some differences in the temperature dependencies obtained under the atomic and polyatomic ion bombardment are observed and interpreted as the indication of different efficiencies of the sputtering process since polyatomic projectiles sputter more material than atomic ones. This, in addition to better surface cleaning, enhances yields of cluster ions. For atomic ions Ta+, an additional emission channel, thermal evaporation/surface ionization, is identified at target temperatures T > 2300 K. No evaporated cluster ions are observed.

A simple design for a cesium sputter ion source compatible with vacuum and ion-optical systems as well as with electronics of the commercially available Cameca IMS-4f instrument is reported. This ion source has been tested with the cluster primary ions of Si(n)(-) and Cu(n)(-). Our experiments with surface characterization and depth profiling conducted to date demonstrate improvements of the analytical capabilities of the secondary ion mass spectrometry instrument due to the nonadditive enhancement of secondary ion emission and shorter ion ranges of polyatomic projectiles compared to atomic ones with the same impact energy.