Spark Source Mass Spectrography Research Articles

Oral histories in meteoritics and planetary science: VI. Stuart Ross Taylor

Abstract— In this interview, Ross Taylor describes how his interest in planetary science was aroused by proofreading Brian Mason's book on geochemistry. Born and raised in New Zealand, Ross majored in chemistry at Canterbury College in Christchurch. While there, he took a course in geology and was strongly tempted to change his major, but he resolved the problem by becoming a geochemist. For his doctoral studies, Ross joined Mason at Indiana University where he learned the basics of trace element analysis on the emission spectrograph. Subsequently, he set up emission spectrographic laboratories and used them to pursue his research at Oxford University and the University of Cape Town. As techniques became more sensitive, he set up a spark‐source mass spectrograph at the Australian National University in Canberra. Ross always has retained an interest in terrestrial rocks, but he is most widely known for his investigations of tektites and lunar rocks. He became one of the earliest and strongest advocates of tektites as molten terrestrial sediments sent aloft by high‐energy impacts. As a member of the preliminary examination team that analyzed the samples returned by the Apollo missions, Ross gained an intimate knowledge of lunar chemistry and petrology and wrote three books about the Moon. He also has written a book about the chemical evolution of the solar system, a topic on which such rapid progress was made in 10 years that his second edition is practically a different book from the first one. Ross has written Destiny or Chance, a philosophical consideration of the likelihood that as sentient beings we may well be alone in the universe. Ross served as the president of The Meteoritical Society in 1989 and 1990, and at its annual meeting in Dublin, Ireland, in 1998, the Society presented him with its Leonard Medal.

Study of α-HgI2 crystals grown in space by differential scanning calorimetry, scanning cathodoluminescence microscopy and optical microscopy

Several α-HgI2 crystals grown in space during the SL3 mission of Spacelab have been analysed: (1) by spark source mass spectrography, (2) by α to β phase transition temperature measurements using differential scanning calorimetry, (3) by scanning cathodoluminescence microscopy, (4) by optical microscopy, and have been compared with other crystals grown on the ground under the same conditions. All the crystals show: (1) an important concentration of inorganic impurities (exceeding 100 at.ppm with respect to Hg), (2) an even larger concentration of carbon bound as hydrocarbons (several hundreds of at.ppm), (3) a deviation from stoichiometry (probably Hg-rich), (4) a characteristic cellular structure having cell diameters ranging from 2 to 6 μm, and (5) growth instabilities, revealed by the presence of many macrosteps and terraces, leading to the formation of grooves and of lens-shaped clusters rich in impurities having diameters ranging from 1 to 6 μm. By comparing the transition temperatures and the average cell diameter of the grown crystals with those of the source polycrystals, we conclude that the composition of the crystals grown in space are closer to the stiochiometric composition than the composition of the crystals grown on the ground.

Large scale synthesis and growth of polycrystalline InP

An apparatus has been designed and constructed for the direct synthesis and growth of polycrystalline indium phosphide by injection of phosphorus through a layer of boron oxide into indium. Two modes of operation were used. In the first, the whole charge was frozen out slowly to form a crucible-shaped ingot which was broken up for use in single crystal growth. A seed crystal was used to prevent supercooling of the melt. In the second, the seed crystal was used to initiate Czochralski growth and the product was removed as a polycrystalline ingot. Details are given of the design features of the apparatus. The electrical properties of the product are presented, as well as analytical results obtained by spark source mass spectrograph.

Comparison of two universal techniques of spark source mass spectrography for the analysis of powdered materials

The efficiency of two universal techniques of spark source mass spectrography (SSMS), the graphite powder technique (GPT) and the aluminium crucible technique (ACT), are compared. Most emphasis is put on the universality, but other features are also taken into account. To assess the matrix effects and their causes in an objective manner, a statistical evaluation based on the two-way analysis of variance (two-way ANOVA) has been carried out. ACT suffers more from matrix effects, but in special cases, e.g. for small sample sizes or to avoid line interferences, it can be recommended after a matrix group-specific calibration.

Residual sulphur and silicon doping in InP and GaInAs

The samples studied here are either InP single crystals grown by the liquid encapsulation Czochralski technique or GaInAs epilayers grown on InP by molecular beam epitaxy or liquid phase epitaxy. They were characterized by secondary ion mass spectrometry (SIMS), Hall effect measurements, spark source mass spectrography (SSMS), and scanning electron microscopy (SEM). Quantitative high resolution SIMS analyses identify sulphur and silicon as background residual donors in these materials, but, it is found that the concentration of sulphur ranging from 4 × 10 15 to 8 × 10 16 cm −3 is about one order of magnitude higher than that of silicon. The donor concentrations determined either from electrical measurements or from SIMS analyses agree to within a factor of two over almost two orders of magnitude. Nevertheless, the behaviour of silicon in InP is still unclear. In homogeneous regions of the crystals, silicon is found by SIMS, at a low concentration, in the 3 × 10 14 –6 × 10 15 cm −3 range. But, sometimes, in regions where microtopographies are visible, perhaps precipitates or inclusions, the silicon concentration grows up to anomalously high levels. This fact is confirmed by bulk SSMS analyses.

Determination of Ultra ‐ Trace Amounts of Thorium in NIM‐D and NIM‐P Standard Geological Reference Materials Using Cation Exchange Chromatography ‐ Spark Source Mass Spectrography

Ultra‐trace (<1 ppm) amounts of thorium in NIM‐D and NIM‐P geochemical reference materials are determined by the technique of cation exchange chromatography ‐ spark source mass spectrography. After dissolution, thorium is selectively separated from all other elements on a column of AG50W‐X4 resin. The thorium eluate is concentrated and evaporated onto silver powder together with 1 000 ng of uranium which serves as the internal standard. Mass spectrographic analysis of this spiked silver powder is carried out with a spark source mass spectrograph.

Geochemical application of spark-source mass spectrography: IV. The crustal abundance of tin

The abundance of tin has been generally underestimated due to the difficulty of dissolving cassiterite, and to the subsequent calibrations of instrumental techniques with standard samples whose Sn values were determined by chemical techniques. Using a spark-source mass spectrometric calibration procedure which is independent of standard samples, we conclude that the abundance of Sn in international rock standards is higher than earlier determinations by factors of 1.5–2. Sn abundance values in the continental crust based on these earlier values have been revised as follows: upper crust, 5.5 ppm; total crust, 2.5 ppm; and lower crust, 1.0 ppm.

Spark source mass spectrographical specification of mixed oxide reactor fuel for metallic and rare earth impurities

This paper describes the adaptation of a spark source mass spectrograph to allow analysis of mixed oxide nuclear reactor fuel (UO 2-PuO 2). It is shown that analyses can be performed on relatively small amounts of sample, using extremely simple and straightforward sample preparation procedures. Nevertheless, detection sensitivities and confidence limits to be assigned to the concentration values certified easily reach the required specifications.

Reply to the critical comments on the paper: “the efficiency of universal techniques of atomic emission spectrography and spark source mass spectrography for analysis of non-conducting powders”

Reply to the critical comments on the paper: “the efficiency of universal techniques of atomic emission spectrography and spark source mass spectrography for analysis of non-conducting powders”

The efficiency of universal techniques of atomic emission spectrography and spark source mass spectrography for the analysis of non-conducting powders

Two semi-quantitative universal techniques for the analysis of very different non-conducting powdered materials were compared with regard to matrix influences on the reliability of the analytical results. One of these techniques is based on atomic emission spectrography (AES) and was proposed by K roonen and V ader[4] several years ago. The other one is based on spark sources mass spectrograpny (SSMS) and has been developed in our laboratory more recently. To evaluate matrix effects objectively, a “total factor of variation”. V tot, was calculated as the antilogarithm of the standard deviation of the logarithms of analytical results over all matrices. The factor was compared by statistical analysis of variance to an analogous factor v rep, estimated in each case from a set of replicate determinations in one matrix and thus representing the precision of the technique. The results show that in the case of the SSMS technique v tot varies from 1.6 to 1.9 and only sometimes exceeds v rep slightly (probability P = 0.95). On the other hand for the AES procedure, v tot varies from 1.4 to 2.3 and always exceeds v rep, with a high significance ( P > 0.99). However, precision is higher in AES. From the results, the conclusion is drawn that SSMS is more suitable for elaboration of universal techniques, in the case of non-conducting powders just as in the case of compact metals.

The distribution of trace elements in carbonaceous chondrites

12 carbonaceous chondrites, amongst them representatives of nearly all known petrologic types were analyzed for twenty trace elements by spark source mass spectrography combined with the isotope dilution method. Data on different element groups (refractory, moderately volatile and volatile) show that the distribution of the trace elements in the carbonaceous chondrites, with the exception of Renazzo, can be well explained by Anders' two-component model. This is also valid for the highly metamorphosed CV5 chondrite Karoonda.Furthermore, it is observed that the ZrHf-ratios in the carbonaceous chondrites increase with increasing petrologic type which is interpreted as the result of mixing two components with different ZrHf-ratios

Evidence d'un lieu privilegie de transfert de charge dans un spectrographie de masse de type mattauch-herzog

Trajectories of charge-exchange ions are calculated in a spark source mass spectrograph. It is assumed that the charge-exchange process M n +→M p + takes place inside the magnetic fringing field extending across the so-called “field-free space” of the Mattauch—Herzog geometry. The calculations involve a line shift versus the expected value M − n/ p 2, given by S = √2 · f · X · ( n− p)/ p, f being the relative intensity of the virtual field representative of the fringing field, and X the projected ion path before charge-exchange occurs. S does not depend on the instrument dispersion or on the ion mass, and is in good agreement with experimental data. This result provides evidence of a privileged location for the charge-exchange process. Hence a collision-induced process is questionable.

Modification of an SSMS ion source to reduce residual gas effects

A simple modification to the spark shield of the ion source of a spark source mass spectrograph is discussed. This helps to maintain a low partial pressure of residual gases during sparking of reactive materials. A grid is placed over the viewing slit to prevent energetic neutrals and ions from striking the walls of the source chamber, thereby desorbing unwanted gases into the ion source chamber. The results show a reduction of an order of magnitude in the total pressure during sparking over the conventional spark shield.

Simultaneous determination of 20 trace elements in geologic samples by the isotope dilution method combined with spark source mass spectrography

Simultaneous determination of 20 trace elements in geologic samples by the isotope dilution method combined with spark source mass spectrography

Auswertung von ionenempfindlichen Photoplatten durch ein computergesteuertes Graukeil-Densitometer / Evaluation of Ion-sensitive Photographic Plates in Using an Optical Wedge Microdensitamiter

Abstract A procedure for the automatic evaluation of ion-sensitive photographic plates used in spark source mass spectrography is described. Using an optical wedge microdensitometer the line-transmittance profiles are measured and stored. In a second step the transmittance profiles are converted into ion-intensity profiles, according to the equation of Franzen et al. [8], and inte-grated. The two methods, peak height and integrated intensities, are compared in terms of precison and accuracy.

The chemical and pyrometallurgical purification of β rhombohedral boron

The purification of boron by electron beam melting and chemical vapour deposition from BI 3 was investigated. The analytical results obtained by spark source mass spectrography are compared and discussed.

Purity of boron prepared by vacuum decomposition of purified boron triiodide

The synthesis, purification and thermal decomposition of boron triiodide have been investigated as a method for preparing high purity boron. Using spark source mass spectrography for the analyses of bulk samples, the purity of boron is studied as a function of the purification treatments applied to BI 3 prior to its decomposition. Bisublimation, recrystallization and, to a higher degree, zone refining of BI 3, result in a noticeable decrease in the levels of almost all impurities except carbon and oxygen. The lowest contamination levels attained are 200 and 470 wt. ppm for carbon and oxygen, respectively and a total content of 150 wt. ppm for the other main impurities. Whereas the latter value could be reduced by improved zone refining of BI 3, lower levels of carbon and oxygen appear very difficult to obtain.

Direct analysis of solid cadmium mercury telluride by flameless atomic absorption using interactive computer processing

This paper describes a solid sampling technique for the quantitative measurement of impurities in cadmium mercury telluride (CMT) in the ppb region. It has been used to calibrate the spark source mass spectrograph (A.E.I. MS7) analysis of this material. Typical detection limits obtained are: 0.0002 ppmw Ag, 0.002 ppmw Cu, 0.001 ppmw Fe, 0.0002 ppmw Mn, 0.002 ppmw Cr, 0.004 ppmw Al, 0.0001 ppmw Na, 0.000 06 ppmw Mg, 0.01 ppmw Si. The solid sample is directly analysed by flameless atomic absorption and the method is shown to give results precise to about 10%. Aqueous standards are used throughout and area measurements are found to be considerably better than peak-height calibration curves for this material. The data collection, calculation and display use a shared computer system developed at these laboratories.

Polarity of breakdowns and properties of ion beams in the self-triggered mode of damped discharges

The effects of breakdown polarity were studied with a spark source mass spectrograph using the self-triggered mode of damped discharges and a special device to suppress the ion beam when the discharge is not of the chosen polarity. Significant results were obtained from experiments on ion production efficiency, energy distribution and time of flight; e.g. ions are produced in the vapour phase from both anode and cathode, the kinetic energy of ions depends on the voltage at the location where they are produced and ions are produced during more than 300 ns in different time phases characteristic of the species.

Determination of trace amounts of rare earth elements in various environmental samples by spark source mass spectrography

水酸化物沈殿分離法とスパークイオン源質量分析法の組み合わせによる各種環境試料中の微量希土類元素の定量法を検討した.相対感度係数はSpex Mix 1031及び米国地質調査所(USGS)の標準岩石G-2を用いて決定した.本法によってUSGSのGSP-1試料及びNBSの石炭フライアッシュの標準試料SRM1633中の微量希土類元素を定量した結果,定量値は文献値と良好な一致を示し,本法は良好な正確度を持っていることが分かった,浮遊粉じん捕集用濾材として一般に用いられているガラス繊維フィルター中の不純物元素としての希土類元素及びポリスチレンフィルター上に捕集された浮遊粉じん,ダストジャー内の降下ばいじん,土じょうなどの各種環境試料中の希土類元素が本法によって定量された.