Relative Sensitivity Factors Research Articles

Investigation of the intensity dependence of glow discharge mass spectrometry quantification on the discharge parameters

Measurements of the absolute intensities of discharge gas and trace elements/isotopes can help to understand the ionization mechanism and contribute to the reduction in uncertainty related to the relative sensitivity factor (RSF).

Rapid and quantitative analysis of impurities in silicon powders by glow discharge mass spectrometry.

High-purity silicon power was doped with standard solutions containing 15 elements, and a high-purity indium tablet was prepared by the melting of indium pellets. An In-Si tablet, which is mechanically stable and thus suitable as a calibration sample, was prepared by our pressing the doped silicon power on the high-purity indium tablet. The matrix effect was studied by our investigating the variations of measured mass fractions (standard relative sensitivity factor, StdRSF, calibration) of doped impurities in the In-Si tablet, which provides a series of matrixes with different mass ratios of In to Si. For all the elements, the relative standard deviations of the measured mass fractions of impurities were less than 30%. The RSFs of the glow discharge mass spectrometer (Element GD) were obtained, and the results showed that three RSFs derived from the In-Si tablet with low, intermediate and high mass ratios of In to Si, respectively, agreed with the mean RSF within an uncertainty interval of 30%. The measurement of Fe and Al matrix certified reference materials further demonstrated that the RSFs generated from a matrix can be used for the calibration of another matrix, and the uncertainty was within 30%. Finally, another doped silicon powder was measured with the glow discharge mass spectrometer, which was calibrated by the mean RSFs from the In-Si tablet, and the analytical results obtained by glow discharge mass spectrometry are in good agreement with the analytical results obtained by high-resolution inductively coupled plasma mass spectrometry. Graphical abstract ᅟ.

Evaluation of Relative Sensitivity Factors for Elemental Analysis of Aluminum and Magnesium Using Glow Discharge Mass Spectrometry with a Fast-Flow Grimm-type Ion Source.

Relative sensitivity factors on glow discharge mass spectrometry were evaluated for unalloyed and alloyed metals of aluminum and magnesium using a glow discharge mass spectrometer operated with fast flow Grimm-type source. All the elements measured could be classified into two groups, i.e. a group of elements could be determined with repeatability equal to or less than 15% relative standard deviation, while another group could be determined with RSDs of greater than 15%. The latter is mainly due to the instability of discharge condition and elemental segregation onto certified reference materials.

Beryllium-boron relative sensitivity factors for melilitic glasses measured with a NanoSIMS ion microprobe

Beryllium-boron relative sensitivity factors for melilitic glasses measured with a NanoSIMS ion microprobe

Pulsed glow discharge enables direct mass spectrometric measurement of fluorine in crystal materials – Fluorine quantification and depth profiling in fluorine doped potassium titanyl phosphate

A pulsed direct current glow discharge time-of-flight mass spectrometry (GD TOF MS) method for the quantification of fluorine in insoluble crystal materials with fluorine doped potassium titanyl phosphate (KTP) KTiOPO4:KF as an example has been proposed. The following parameters were optimized: repelling pulse delay, discharge duration, discharge voltage, and pressure in the discharge cell. Effective ionization of fluorine in the space between sampler and skimmer under short repelling pulse delay, related to the high-energy electron impact at the discharge front, has been demonstrated. A combination of instrumental and mathematical correction approaches was used to cope for the interferences of 38Ar2+ and 1H316O + on 19F+. To maintain surface conductivity in the dielectric KTP crystals and insure its effective sputtering in combined hollow cathode cell, silver suspension applied by the dip-coating method was employed. Fluorine quantification was performed using relative sensitivity factors. The analysis of a reference material and scanning electron microscope-energy dispersive X-ray spectroscopy was used for validation. Fluorine limit of detection by pulsed direct current GD TOF MS was 0.01mass%. Real sample analysis showed that fluorine seems to be inhomogeneously distributed in the crystals. That is why depth profiling of F, K, O, and P was performed to evaluate the crystals' non-stoichiometry. The approaches designed allow for fluorine quantification in insoluble dielectric materials with minimal sample preparation and destructivity as well as performing depth profiling to assess crystal non-stoichiometry.

Relative sensitivity factors in hard X‐ray photoelectron spectroscopy

Empirical relative sensitivity factors (RSFs) for the 1s, 2s, 2p3/2, and 3d5/2 levels relative to O1s were derived from the hard X‐ray photoelectron spectroscopy measurements. Comparing with the theoretical RSFs calculated from Hartee‐Slater cross sections reported by Scofield with combined energy dependence on the spectrometer function and the inelastic mean free path, the sublinear behaviors as a function of the binding energy on a log‐log plot and the good agreement between the empirical and the theoretical RSF values were observed with several notable exceptions, while the discrepancies between the empirical and the theoretical RSFs were observed in several energy regions. In addition, we estimated the experimentally based RSFs by the power law fitting of the empirical RSFs.

Multitechnique elemental depth profiling of InAlGaN and InAlN films

This work shows the capabilities of the plasma profiling time of flight mass spectrometry (PP-TOFMS) for the determination of elemental composition and distribution in InAlGaN thin films used for high electron mobility transistors. The PP-TOFMS results have been compared with wavelength dispersive x-ray fluorescence analyses for the elemental composition determination and with x-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry (TOF-SIMS) for elemental distributions. Relative sensitivity factors have been developed for the comparison of PP-TOFMS with TOF-SIMS results. The PP-TOFMS was able to determine the relative composition of In and Al in the thin films with an accuracy of 10 rel. % without calibration. Depth profiles acquired from the PP-TOFMS technique were obtained within a few minutes and exhibited very similar In, Al, and Ga distributions to TOF-SIMS measurements, and thus PP-TOFMS has been shown to be a valuable addition to TOF-SIMS analysis for a fast process development.

IQuant2: Software for Rapid and Quantitative Imaging Using Laser Ablation-ICP Mass Spectrometry.

We report on the development of a software program named iQuant2 which creates visual images from two-dimensional signal intensity data obtained by a laser ablation-ICP-mass spectrometry (LA-ICPMS) technique. Time-resolved signal intensity profiles can be converted to position resolved signal intensity data based on the rastering rate (μm s−1) of the laser ablation. Background signal intensities obtained without laser ablation (gas blank) are used as the background, and all of the blank-subtracted intensity data can be used for the imaging analysis. With this software, deformation of the created image can be corrected visually on a PC screen. The line profile analysis between the user-selected points can be observed using the iQuant2 software. To accomplish this, data points on the profile line were automatically calculated based on the interpolation between the analysis points. The resulting imaging data can be exported and stored as JPEG, BMP or PNG formats for further processing. Moreover, a semi-quantitative analysis can be made based on the coupling of the external correction of the RSF (relative sensitivity factor) using NIST SRM610 with normalization of the corrected signal intensity data being 100%. The calculated abundance data for major elements are in reasonable agreement with the values obtained by electron probe micro analyzer (EPMA). With the software developed in this study, both the rapid imaging and semi-quantitative determinations can be made.

Impact ionisation mass spectrometry of platinum-coated olivine and magnesite-dominated cosmic dust analogues

Impact ionisation mass spectrometry enables the composition of cosmic dust grains to be determined in situ by spacecraft-based instrumentation. The proportion of molecular ions in the impact plasma is a function of the impact velocity, making laboratory calibration vital for the interpretation of the mass spectra, particularly at the low velocities typical of lunar or asteroid encounters. Here we present an analysis of laboratory impact ionisation mass spectra from primarily low (<15 km s−1) velocity impacts of both olivine and magnesite-dominated particles onto the SUrface Dust Mass Analyzer (SUDA) laboratory mass spectrometer.The cation mass spectra show characteristic peaks due to their constituent elements, with Mg, Al, Si, C, Ca, O and Fe frequently present. Contaminant species from the conductive coating process (B, Na, K, C, Pt) also occur, at varying frequencies. Possible saponite or talc inclusions in the magnesite particles are revealed by the presence of Si, Fe, Ca and Al in the magnesite mass spectra. Magnesium is clearly present at the lowest impact velocities (3 km s−1), at which alkali metals were presumed to dominate. Peaks attributed to very minor amounts of water or hydroxyl present in the grains are also seen at low velocities in both cation and anion mass spectra, demonstrating the feasibility of impact ionisation mass spectrometry in identifying hydrated or hydrous minerals, during very low velocity encounters or with very low abundances of water or hydroxy groups, in the impinging grains.Velocity thresholds for the reliable identification of the major elements within the magnesite and olivine cation spectra are presented. Additionally, relative sensitivity factors for Mg (5.1), Fe (1.5) and O (0.6) with respect to Si, in the olivine particles, at impact speeds >19 km s−1, were found to be very similar to those previously determined for orthopyroxene-dominated particles, despite different target and projectile materials. This confirms that quantitative analyses of mineral dust grain composition in space is viable despite initially poorly-constrained mineralogy.

Facile preparation of CeO2 microspheres with high surface area by ultrasonic spray pyrolysis

AbstractCeCl3solution was used as a precursor to prepare CeO2microspheres by ultrasonic spray pyrolysis (USP). This is a green process that allows the transformation from CeCl3to CeO2without consuming any precipitant. The prepared material was investigated through various analysis technologies, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS), N2adsorption-desorption and X-ray photoelectron spectroscopy (XPS). The prepared sample was confirmed as high purity CeO2microspheres, and two different microstructures were observed. The microsphere surface area was 86.5 m2/g according to the Brunauer-Emmett-Teller method. The microsphere diameter ranged from 0.09 μm to 3.86 μm and the microsphere surface was covered by numerous nanoparticles. The observed nanoparticles ranged in size from 19 nm to 200 nm as determined from FESEM and HRTEM images. The concentrations of Ce4+, Ce3+, residual chloride and oxygen vacancy in CeO2were studied by relative sensitivity factors based on the XPS results. Finally, the data suggested the possible formation mechanism of the CeO2microsphere structure.

Uncertainty of relative sensitivity factors in glow discharge mass spectrometry

The concept of the relative sensitivity factors required for the correction of the measured ion beam ratios in pin-cell glow discharge mass spectrometry is examined in detail. We propose a data-driven model for predicting the relative response factors, which relies on a non-linear least squares adjustment and analyte/matrix interchangeability phenomena. The model provides a self-consistent set of response factors for any analyte/matrix combination of any element that appears as either an analyte or matrix in at least one known response factor.

Quantitative analysis of Si1-xGex alloy films by SIMS and XPS depth profiling using a reference material

Quantitative analysis methods of multi-element alloy films were compared. The atomic fractions of Si1-xGex alloy films were measured by depth profiling analysis with secondary ion mass spectrometry (SIMS) and X-ray Photoelectron Spectroscopy (XPS). Intensity-to-composition conversion factor (ICF) was used as a mean to convert the intensities to compositions instead of the relative sensitivity factors. The ICFs were determined from a reference Si1-xGex alloy film by the conventional method, average intensity (AI) method and total number counting (TNC) method. In the case of SIMS, although the atomic fractions measured by oxygen ion beams were not quantitative due to severe matrix effect, the results by cesium ion beam were very quantitative. The quantitative analysis results by SIMS using MCs2+ ions are comparable to the results by XPS. In the case of XPS, the measurement uncertainty was highly improved by the AI method and TNC method.

Round‐robin test for the measurement of layer thickness of multilayer films by secondary ion mass spectrometry depth profiling

An international round‐robin test (RRT) was performed to investigate a method to determine the interface location and the layer thickness of multilayer films by secondary ion mass spectrometry (SIMS) depth profiling as a preliminary study to develop a new work item proposal in ISO/TC‐201. Two types of reference materials were used in this RRT. A SiGe alloy (Si52.4Ge47.6) reference film was used to determine the relative sensitivity factors of Si and Ge. A Si/Ge multilayer reference film was used to determine the relative sputtering rates of the Si and Ge layers. The layer thicknesses were measured from the interfaces determined by a 50 atomic percent definition. Seven laboratories from 5 countries participated in this international RRT. The RRT reference expanded uncertainties for Si and Ge layers in a Si/Ge multilayer with similar thicknesses as the reference film were 0.76 and 1.17 nm, respectively. However, those in a thinner Si/Ge multilayer film were slightly larger at 1.04 and 1.59 nm, respectively. Most of the thickness ratios in the 2 Si/Ge multilayer films were consistent with the RRT reference value within their expanded uncertainties.

Rare earth element abundances in presolar SiC

Individual isotope abundances of Ba, lanthanides of the rare earth element (REE) group, and Hf have been determined in bulk samples of fine-grained silicon carbide (SiC) from the Murchison CM2 chondrite. The analytical protocol involved secondary ion mass spectrometry with combined high mass resolution and energy filtering to exclude REE oxide isobars and Si-C-O clusters from the peaks of interest. Relative sensitivity factors were determined through analysis of NIST SRM reference glasses (610 and 612) as well as a trace-element enriched SiC ceramic. When normalised to chondrite abundances, the presolar SiC REE pattern shows significant deficits at Eu and Yb, which are the most volatile of the REE. The pattern is very similar to that observed for Group III refractory inclusions. The SiC abundances were also normalised to s-process model predictions for the envelope compositions of low-mass (1.5–3 M⊙) AGB stars with close-to-solar metallicities (Z=0.014 and 0.02). The overall trace element abundances (excluding Eu and Yb) appear consistent with the predicted s-process patterns. The depletions of Eu and Yb suggest that these elements remained in the gas phase during the condensation of SiC. The lack of depletion in some other moderately refractory elements (like Ba), and the presence of volatile elements (e.g. Xe) indicates that these elements were incorporated into SiC by other mechanisms, most likely ion implantation.

Matrix effects on the relative sensitivity factors for manganese and chromium during ion microprobe analysis of carbonate: Implications for early Solar System chronology

The short-lived radionuclide 53Mn decays to 53Cr providing a relative chronometer for dating the formation of Mn-rich minerals in meteorites. Secondary ion mass spectrometry (SIMS) has been extensively used for in situ dating of meteoritic olivine and carbonate by the 53Mn–53Cr system, however a significant analytical challenge has been realising accurate measurements of the Mn/Cr ratio in individual minerals of differing chemical compositions. During SIMS analysis, elements are ionised with differing efficiencies and standard materials are required to calibrate measured ion intensities in terms of relative elemental concentrations. The carbonate system presents a particular analytical difficulty since such standards are not naturally available due to low and variable Cr contents. Here, we utilise ion implantation of Cr into carbonate and other phases to accurately determine the relative sensitivity factors of Mn/Cr during SIMS analysis. We find significant variations in Mn/Cr RSF values among different carbonate minerals that depend systematically on chemical composition and we propose an empirical correction scheme that quantitatively yields an accurate RSF for carbonates of diverse chemical compositions. Correction of SIMS carbonate data for this strong matrix effect may help to reconcile some outstanding problems regarding the timescales of aqueous alteration processes in carbonaceous chondrites. Mn–Cr ages, revised based our new understanding of the matrix effect, are, in general, earlier than previously thought and the duration of carbonate formation is shorter.

53Mn–53Cr chronology of Ca–Fe silicates in CV3 chondrites

High precision secondary ion mass-spectrometry (SIMS) analyses of kirschsteinite (CaFeSiO4) in the reduced CV3 chondrites Vigarano and Efremovka yield well resolved 53Cr excesses that correlate with 55Mn/52Cr, demonstrating in situ decay of the extinct short-lived radionuclide 53Mn. To ensure proper correction for relative sensitivities between 55Mn+ and 52Cr+ ions, we synthesized kirschsteinite doped with Mn and Cr to measure the relative sensitivity factor. The inferred initial ratio (53Mn/55Mn)0 in chondritic kirschsteinite is (3.71±0.50)×10–6. When anchored to 53Mn–53Cr relative and U-corrected 207Pb–206Pb absolute ages of the D’Orbigny angrite, this ratio corresponds to kirschsteinite formation 3.2-0.7+08Ma after CV Ca-, Al-rich inclusions. The kirschsteinite data are consistent within error with the data for aqueously-formed fayalite from the Asuka 881317 CV3 chondrite as reported by Doyle et al. (2015), supporting the idea that Ca–Fe silicates in CV3 chondrites are cogenetic with fayalite (and magnetite) and formed during metasomatic alteration on the CV3 parent body. Concentrically-zoned crystals of kirschsteinite and hedenbergite indicate that they initially formed as near end-member compositions that became more Mg-rich with time, possibly as a result of an increase in temperature.

Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS.

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage or sample preparation resulted in a variability in thickness of 53 %. The calculation method chosen by XPS participants contributed a variability of 67 %. However, variability of 12 % was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors, since this contributed a variability of 33 %. The results from the LEIS participants were more consistent, with variability of less than 10 % in thickness and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

Elemental areal density calculation and oxygen speciation for flat glass surfaces using x-ray photoelectron spectroscopy

The elemental composition of multi-component glass surfaces is often insufficient for understanding the effects of surface treatments on properties. For this reason, a data analysis protocol has been developed to quantify the areal density of elements and to determine the oxygen speciation on glass surfaces by X-ray photoelectron spectroscopy (XPS) for flat glass surfaces on which other methods such as optical spectroscopy and thermal analysis cannot be applied due to their low surface area, surface contamination, insufficient signal, etc. Various oxygen species (hydroxyls, non-bridging oxygen, and bridging oxygen) are distinguished and quantified using a simple workflow involving the determination of accurate elemental relative sensitivity factors, adventitious hydrocarbon contamination correction, and the conversion of the corrected elemental glass composition to areal elemental density. The areal density of oxygen species is obtained by a standard glass model based stoichiometry approach and compared with a constrained peak fitting of the O 1s photoelectron spectrum. The data analytical protocol is first verified with a silica glass, and then applied to pristine re-melt surfaces and acid-leached surfaces of commercial multi-component silicate glasses. XPS analysis revealed that upon leaching, significant repolymerization of network oxygen is observed in the calcium aluminosilicate glass surface in contrast to the lack of restructuring in the soda-lime silica glass surface.

Development of simple high-precision two-dimensional dose-distribution measurement method for proton beam therapy using imaging plate and EBT3.

Although there are several two-dimensional (2D) dose-distribution measurement methods using proton beam therapy, they all have drawbacks; hence, there is no standard method established worldwide. The purpose of this study was to develop a simple, high-precision 2D distribution measurement method for proton beam therapy that uses an imaging plate and EBT3. First, we expanded the maximum readable dose (saturation dose) in the imaging plate. The method involves (i) the control of the fading phenomenon by an annealing process and (ii) the control of the photostimulated luminescence (PSL) phenomenon using a longpass filter (LPF). In method (i), upon heating at 80°C, the PSL became 0.485 times the room temperature, and in method (ii), we attenuated the PSL by a factor of 0.245 using an LPF. Thus, by combining methods (i) and (ii), we expanded the saturation dose to 2Gy. Thus, it was possible to measure the imaging plate and EBT3 in the same dose range. We simultaneously measured the percent depth dose using imaging plate and EBT3. We defined a correction factor to match the measured values-which had a reduced sensitivity because of the linear energy transfer (LET) dependence of the imaging plate and EBT3-with reference data and developed a correction factor function. Subsequently, by defining the relative LET dependence of imaging plate and EBT3 as the relative sensitivity and converting the relationship imaging plate between the relative sensitivity and correction factor into a function, we obtained a sensitivity-correction function. By employing this function, measurements with the same accuracy as the reference data were performed using the imaging plate and EBT3.

Micro-scale (∼10 μm) analyses of rare earth elements in silicate glass, zircon and apatite with NanoSIMS

Micron-scale (∼10μm) analyses of rare earth elements (REEs) in silicate glass, zircon and apatite were carried with nano-scale secondary ion mass spectrometer (NanoSIMS) operating at high mass resolution mode (m/Δm=∼10000, 10%), which eliminating isobaric interferences of heavy REEs by light REE monoxides. To achieve high lateral resolution, the primary O− probe was optimized to a current of ∼1nA and a diameter<2.5μm, scanning over the analysis area of 5×5μm2 or 10×10μm2. The analyses were conducted at a combined mode of multi-collection and peak-jumping to improve the analytical efficiency. Fifteen ion species including rare earth elements and a reference element (Si or Ca) were counted through 4 times of magnetic field switch. The standards of NIST glass, apatite and zircon were analyzed in this study, which represent flat patterns, LREE-enriched and LREE-depleted and show different matrix effects. The relative sensitivity factors (RSF) of REEs are higher in zircon than NIST glass by a factor of 20–50% referred to 30Si+, and they are higher in apatite than NIST glass by a factor of 2–3 referred to 42Ca+. Therefore, the absolute concentration of REEs could be only calibrated with the matrix-matched mineral standards in the SIMS analysis. The analytical reproducibilities (1SD) were <5% for silicate glass (NIST SRM 610), <10% for apatite (Durango) and <15% for zircon (M257). The analytical accuracies determined from the measurements of the standards NIST glass (NIST SRM 612), apatite (MAD and Otter lake) and zircon (91500) were better than 10%, 20% and 30%, respectively, except for La interfered by ZrSiO and ZrO3 for zircon.