Source Mass Spectrometer Research Articles

Reactivities of propane and propene with monopositive ions of fourth period elements produced in a spark

The fractional ion current of MCH 3 + ions formed by the reaction of monopositive ions M + of the elements of the fourth period with propane and propene in a spark source mass spectrometer is correlated inversely with the energy gap between a 4 s 1 ground state and the lowest excited state of a different configuration; or, if the element does not have a 4 s 1 ground state, directly with the energy gap between the ground state and the lowest 4 s 1 excited state, paying heed to the effect of more highly excited 4 p states. This correlation is taken as further evidence for the intervention of excited states of metal ions in the chemistry of metals and organic molecules and supports the hypothesis that metal ions insert in carbon-carbon bonds via an s 1 state.

An improved high-pressure, temperature-variable ion source with coaxial electron beam/ion exit slit

A new mass spectrometer ion source has been developed to study high-pressure ion molecule kinetics and equilibria as a function of temperature. Unlike conventional mass spectrometer sources, the present source has coaxial electron entrance and ion exit apertures. Ions move through the source at a constant velocity due to the presence of a constant drift potential gradient. Low drift fields are used to minimize non-thermal conditions. The effect of the field on ion energy is discussed. As both a demonstration and a test of the source operation, mobilities of ions in gases were studied as a function of drift field, pressure and temperature. Good agreement was obtained with previously reported mobility measurements. The ternary association reaction N 2 + + 2N 2 → N 4 + + N 2 and the equilibrium CO 2 + + 2CO 2 ⇆ (CO 2) 2 + + CO 2 were also investigated as a function of temperature and pressure. Again, good agreement between literature values and these experiments was obtained.

Evaluation and application of the ion microprobe in the strontium isotope geochemistry of carbonates

A modified AEI-IM20 ion microprobe has been used to measure 87Sr/ 86Sr ratios in carbonates. A suite of carbonates with varying major elements (Ca, Mg, Fe, Mn) was studied at low and high ( M/ΔM ⋍ 3000) mass resolution to determine the types and intensities of molecular species isobaric with Sr peaks; Sr data collected at low mass resolution must be corrected for Ca 2 and CaMgO species. Rb/Sr ratios are extremely low, and correction for 87Rb is not required (< 0.1‰ of 87Sr). Usable Sr isotopic data may be obtained from calcite given Sr≥ 400ppm, and for Sr > 5000 ppm a precision of ∼ ± 1‰ (± 0.0007) in 87Sr/ 86Sr (2σ mean) can be achieved under optimum conditions. The corrections for Ca 2 and CaMgO are smaller than the within-run precision in calcite, but in dolomite the correction for CaMgO is + 1.5%. Mass fractionation corrections to 87Sr/ 86Sr (based on 86Sr/ 88Sr= 0.1194) are typically +8 to +10‰. Good agreement between ion probe and solid source mass spectrometer results was found for calcites of known Sr isotopic composition: ST4a (∼ 400ppm Sr), average ion probe 87Sr/ 86Sr= 0.7267 ± 0.0015, solid source 87Sr/ 86Sr= 0.72680 ± 0.00008 [14]; JCG36 (∼ 6000ppm Sr), average ion probe 87Sr/ 86Sr= 0.7056 ± 0.0009, solid source 87Sr/ 86Sr= 0.70588 ± 0.00009 [16]; JCG44 (∼ 6000ppm Sr), average ion probe 87Sr/ 86Sr= 0.7057 ± 0.0006, solid source 87Sr/ 86Sr= 0.70540 ± 0.00008 [16]. The ability of the ion microprobe to measure 87Sr/ 86Sr for 10-μm spots in calcite was used: (1) to measure variation in 87Sr/ 86Sr of ∼ 0.01 on a centimetre scale in a hydrothermally altered basalt from the Isle of Skye, northwestern Scotland; and (2) to determine the Sr isotopic composition of tiny (< 35 μm) calcite grains in a veined mantle lherzolite from Bultfontein, South Africa. Because of calcite's ubiquitous occurrence in many parageneses this technique may offer many opportunities for the measurement of fine scale heterogeneities in 87Sr/ 86Sr.

Cumulative yields of stable and long-lived isotopes of tin in neutron-induced fission

The relative cumulative fission yields of the six stable isotopes of tin (117Sn,118Sn, 119Sn, 120Sn, 122Sn, and 124Sn) and the long-lived isotope 126Sn have been measured in the thermal and epicadium neutron fission of 233U and 235U, and the epicadium neutron fission of 238U. Nanogram-sized fission product tin samples were extracted from irradiated uranium samples and analyzed in a solid source mass spectrometer. In each case a smooth curve can be drawn through the yield points of the seven isotopes of tin. There is, therefore, no evidence of "fine structure" in the 117 ≤ A ≤ 126 portion of the symmetric mass region.

Reactions of carbonyl compounds and group 1b metals in a plasma in the wake of a spark

The reaction of the model system of C 3H 6 and Cu to produce cationized species C n,H m,Cu + in the spark source mass spectrometer proceeds through neutral organic species and Cu +. On this basis reactions of Cu +, Ag + and Au + with neutral methyl, ethyl and propyl ethanoate, butanone, butanal, 2,4-pentanedione, ethanoic acid and ethanoic anhydride are compared with reactions of similar compounds with laser-generated Cu + in an ion cyclotron resonance spectrometer. In the wake of the spark more fragmentation of the cationized organic species is observed. The simple cationized molecule is not observed if the metal ion has low-lying excited states.

Reactions of group 1b metal ions with selected hydrocarbons in the source of a spark source mass spectrometer

Evidence for the intervention of excited states of Au +, Ag + and Cu + in chemical reactions is gathered from differences in the chemistry of the interaction of these ions with hexane, cyclohexene, benzene and propene, and of Au + only with butadiene and cyclohexane. Most ions are explained by insertions into CC bonds; only in the case of Au + is there unequivocal evidence for insertion into CH bonds. The products of decyclotrimerization reactions dominate the Au + and Cu + spectra of cyclohexene and benzene, and the Au + spectrum of cyclohexane.

Time-resolved measurements in spark source mass spectrometry. I. Deflection of the ion beam

The synchronous passer system of a JEOL spark source mass spectrometer was modified so that the ion beam could be deflected at a variable time after the start of the first of a series of discharges. The transmitted part of the ion beam was analyzed by photoplate detection. Time-resolved measurements revealed a different behaviour between different ionic species of the same m/z value. The singly-charged atomic ions were delayed by (150±100) ns with respect to the multiply-charged ions. Molecular ions were found to be delayed by about 700 ns (C n +) or even one or more μs (S n +, SC n +) relative to multiply-charged ions. The duration of the production/extraction process of multiply- and singly-charged ions was well defined in time, while this process could last for several μs in the case of polyatomic ions.

Influence of ion energy distributions and matrix effects on spark source mass spectrometric analysis

The energy distributions of ions produced in a spark source mass spectrometer were recorded for different trace element ions and for the total ion current. Both electrodes of pure doped graphite, and with 10% potassium salts added, were examined. The results show that the measured energy of an ion is mainly determined by the m/z ratio and that the energy of the total ion current depends on the sample composition. It was also clear that if the accelerating voltage is set to obtain maximum transmission of the total ion current, the fraction of the heavy elements that is discriminated at the β-slit depends on the matrix composition if the pass band of the instrument is narrow. These effects influence considerably the accuracy in the analysis of variable samples.

Application of isotope dilution mass spectrometry to the determination of cu, cd, pb, zn, ni, fe and cr in seawater

Isotope dilution using a thermal source mass spectrometer (TSMS) has been applied to the investigation of natural levels of Cu, Cd, Pb, Zn, Ni, Fe and Cr in seawater. Multielement analysis can be performed in a single experiment as the release spectra of the elements tend to be staggered with filament current. A single Re filament with a silica gel/phosphoric acid substrate allowed high precision (0.1–0.5%) in the determination of a single ratio and low detection limits (from 0.02 pg for Cd or Pb to 4 pg for Fe). Two isotopic spikes per element were used where possible to allow yield and concentration to be determined in a single experiment. Blanks, assessed as the summation of individually measured components ranged from 0.02 mg kg −1 for Cd, 0.1–0.5 ng kg −1 for Pb, 1 ng kg −1 for Cu, 2 ng kg −1 for Zn to 40 ng kg −1 for Fe, a level made possible by ultra-clean room techniques. Seawater, collected from relatively low lead, coastal waters, was stored acidified in rigorously cleaned, conventional polyethylene carboys at pH 2.0, pH 1.6 and pH 1.1. Extraction of seawater stored at a pH of 1.6–2.0 by dithizone in chloroform and/or by APDC/DDC in Freon TF appeared to yield values representing the dissolved fraction. A rigorous aqua regia digestion of seawater was required for the determination of total values. The precision in the determination of Cd and Zn in seawater was ca. 1%, a level approaching the precision attainable in a single ratio determination (approximately 0.1–0.5%). Moreover, this precision includes the contamination levels incurred in storing seawater for over one year. The precision for lead results varied from 5% at concentrations of 9 ngPb kg −1 to approximately 1% at levels of 30 ng kg −1. The determination of Cu, Ni and Fe were hampered by isobaric interferences. These interferences could be minimized or eliminated by a purification of the final extract with a ‘mini’ ion exchange step and/or by the evaluation of trends in mass spectrometrically determined ratios with time and with filament current. Analyses of comparable amounts of Cd, Pb and Zn in NBS standard 1643a corroborated the accuracy of the IDMS approach/dithizone extraction procedure for these metals at least. Comparison of the seawater results with FAA and ASV methods indicated that for Cd, Pb and Zn, the IDMS approach was the most precise and the most accurate. For Cu, Ni, Fe and Cr extraction difficulties or isobaric interferences have yet to be resolved.

Thermogravimetry coupled with atmospheric pressure ionization mass spectrometry. A new combined technique

Although thermogravimetry has proven to be an extremely useful analytical technique, there are cases where the compositional information derived from this technique is insufficient. A combined thermogravimetric-mass spectrometric technique might be useful to analyze the effluent gases. In an ideal world, the thermogravimetric analyzer would feed directly into the mass spectrometer source. In actual practice, however, flowing gases from the thermogravimetric analyzer are incompatible with the vacuum necessary for mass spectrometer operation. This study presents a new approach to this problem: interfacing the thermogravimetric analyzer to a mass spectrometer designed for atmospheric pressure chemical ionization (APCI). This combined system has demonstrated the ability to distinguish between groups of samples having similar thermogravimetric behavior.

Scanning electron microscope surface observations of electrodes sparked in a spark source spectrometer

Surfaces of electrodes, sparked in a spark source mass spectrometer, have been investigated by scanning electron microscopy. Different patterns, typical for each kind of material have been found. They show incontrovertibly that during sparking thin molten layers with a composition different from the bulk sample must be present. It is suggested that the composition of the plasma is also different from that of the bulk sample. Increasing concentrations of impurities reduce the sharpness of the patterns and influence the directions of the microprotrusions, which themselves depend on the kind of sparked material.

Aluminum and gold-plated aluminum high-pressure mass spectrometer sources

(8) Cooperus, P. A.; Clague, A. D. H.; van Dongen, J. P. C. M. Org. Magn.Reson.1976, 8,426-431. (9) Shoolery, J. N. Prog. Nucl. Magn. Reson. Specfrosc. 1977, 77, 79-93. (IO) Lindon, J. C.; Ferrige, A. G. Prog. Nucl. Magn. Reson. Spectrosc. lS80, 74, 27-66. (1 1) Shaw, D. Fourier Transform NMR Spectroscopy; Elsevier: Amster(12) Becker, E. D. High Resolution NMR, 2nd ed.; Academic Press: New York, 1980; p 229.

Kinetics, equilibria and diffusion of ions produced in N2, CO and CO2, studied as a function of temperature using a high-pressure pulsed mass spectrometer source

Gas phase ion–molecule association reactions of the type A++ A [graphic omitted] A˙ A+ have been studied as a function of temperature in a pulsed electron beam high-pressure mass spectrometer source. Unlike previous studies of this type, the effect of ionic diffusion on the measured pseudo-first-order ion decay is measured and accounted for when estimating kf. Experiments were performed in the ranges 67–399 N m–2 and 365–530 K. At 300 K values of kf were found to be 4.52 × 10–29 and 1.33 × 10–28 molecules–2 cm6 s–1 for N+˙4 formation in N2 and (CO)+˙2 formation in CO, respectively. When expressed in the form kf=CTm, the values of m were found to be –3.8 ± 0.3 and –3.3 ± 0.2, a factor of two larger than the most recent literature values in each case.The equilibrium CO+˙2+ 2CO2rlarr;(CO2)+˙2+ CO2 was also observed for which the values of ΔH=–66.1 ± 2.9 kJ mol–1 and ΔS=–95.4 ± 4.6 J K–1 mol–1 were found, in good agreement with other literature values, leading to ΔHf[(CO2)+˙2]= 475.3 ± 2.5 kJ mol–1.The diffusion coefficients of N+˙2 in N2 and CO+˙ in CO were found to be almost identical, as were those of N+˙4 and (CO)+˙2 over the range of temperatures studied. The fact that the dimer ions have larger coefficients than the monomer is consistent with the role played by resonance charge transfer in the transport of ions. Temperature dependences are, on the whole, lower than expected from theory.

Computer-controlled electrical detection system for a spark source mass spectrometer

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComputer-controlled electrical detection system for a spark source mass spectrometerL. S. Dale, I. Liepa, P. S. Rendell, and R. N. WhittemCite this: Anal. Chem. 1981, 53, 14, 2288–2291Publication Date (Print):December 1, 1981Publication History Published online1 May 2002Published inissue 1 December 1981https://doi.org/10.1021/ac00237a036RIGHTS & PERMISSIONSArticle Views20Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (392 KB) Get e-Alerts Get e-Alerts

Molecular beam facility for studying mass spectrometer performance

An apparatus is described which produces neutral gas beams in the velocity range from thermal to 6 km/s. This facility makes possible studies simulating the motion of instruments through tenuous atmospheres. The use of the apparatus in studying the response of an open-source mass spectrometer similar to those carried on high-speed spacecraft, such as earth satellites or planetary probes for investigating ambient atmospheric composition, is examined. Experiments performed included ones of response of an open source mass spectrometer when: (a) the instrument was in a normal mode of operation; (b) the instrument’s ion source potentials were adjusted so as to reject gas particles which struck instrument surfaces; (c) the gas beam was restricted so that selected portions of the ion source were struck; and (d) the gas beam struck the ion source at angles other than normal incidence.

Study of the pyrolysis of polystyrenes: II. Study of transfer reactions by identification of the most important by-products

Two experimental settings have been used to identify the products of the pyrolysis of polystyrene: (1) a flash pyrolysis cell coupled with a gas chromatograph-mass spectrometer system and (2) an independent pyrolysis cell giving pyrolysate that is identified in the same way. Almost every product with a mass less than that of the dimer was identified. The products with masses between those of the dimer and trimer were grouped by families. Flash pyrolysis led to yields of monomer and trimers greater than those obtained by ordinary pyrolysis and smaller yields of mono- and diphenyl compounds. The observed mass deficit is due to oligomers, which were separately detected by direct introduction of the sample into the mass spectrometer source. The dependence of the yields of the most abundant compounds on temperature between 500 and 900°C was established. The best yield of styrene monomer was 80% at 800°C. The possible mechanisms of formation of the most abundant compounds discussed. Intramolecular transfers seem to be responsible for the production of toluene, 1,3-diphenylpropane, 2,4-diphenyl-1-butene and 2,4,6-triphenyl-1-hexene.

Ultrahigh vacuum cryostat for spectroscopy and laser‐induced processes

AbstractAn ultrahigh vacuum cryostat consisting of a stainless steel body flanged to an analyzer cell for spectroscopy and laser‐induced processes in the entire spectral region between ca. 50 and 0.2 μm at base pressures in the low 10−10 mbar range and sample temperatures between 10 and 600 K is described for the first time. ‐ Under helium bath operation, (4 ± 1) K was measured on the sample holder and (10 ± 2) K in the sample without using thermal contact materials. The metal to metal joint between helium reservoir (stainless steel) and sample holder (OFHC copper) according to the conflat flange method proved to be tight for many baking cycles. The integral leak rate of the whole ultrahigh vacuum apparatus as well as the optical transmission are reported. The windows developed do not show irradiation effects at peak intensities of 10 MW · cm−2 per CO2 laser pulse. The cryostat is equipped with a quadrupole mass spectrometer and evaporation sources for salts and metals. The analyzer cells are compatible with the sample chamber dimensions of most commercial spectrometers. ‐ Examples of applications are presented in the fields of low temperature gassolid interaction, cryospectroscopy of stable and new metastable adsorbates, selective and efficient evaporation and desorption induced by laser infrared.

Mass correction factor of a solid source mass spectrometer for the measurement of absolute lead isotope ratio

Mass correction factor of a solid source mass spectrometer for the measurement of absolute lead isotope ratio

Laser induced multiphoton ionization mass spectrum of benzene

Gas phase benzene is multiphoton ionized under low pressure, collision-free conditions in the source region of a time of flight mass spectrometer using UV excimer laser radiation. All of the ions generated are identifiable and derive from C6H6. The differences between KrF and ArF laser induced mass spectra and total ionization yields are interpreted on the basis of known fragment ion appearance potentials, and a rate equations model which describes the ionization process. The observed mass spectra exhibit certain characteristics not found in conventional electron impact spectra. These idiosyncracies may enhance its potential as a mass spectrometric ionization source.

The effect of trace gases on neodymium ion formation

During measurements of Nd isotope abundances, significant ionization suppression and enhancement effects have been observed and correlated with the presence of oxygen and water vapour in the ion source region of a solid source mass spectrometer. These effects are of particular interest at present because many laboratories are developing the SmNd technique for use in geochronological studies.