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This paper describes advances in isotopic measurements that have been made with an inductively coupled plasma source magnetic sector multiple collector mass spectrometer and presents results of new experiments aimed at further evaluating the instrument's capability. It is shown using standard solutions that trace element ratios such as Rb can be measured precisely without isotope dilution by comparison...
The use of time-of-flight (TOF) mass analysers in the second stage of tandem mass spectrometers employing high energy collision-induced fragmentation is considered. The challenge of achieving detection of all fragment ions and unit mass resolution (in the mass range up to, say, 2000 m/z) cannot be successfully met by traditional reflectrons, because of the huge energy spread of the fragment ions...
Electron attachment mass spectra of the products of fluoroalkyl radical additions to C 60 show intense molecular ions as well as ions produced by attachment of two electrons to the gas phase molecules. Remarkably, little fragmentation is observed for these fluorocarbon derivatized fullerenes, suggesting that electron attachment is occurring on the highly electron deficient C 6 ...
Recent experimental and theoretical studies on the successive ionization energies of C 60 yield rather divergent dependences on the charge state z. The present mass spectrometric investigation on the super-asymmetric charge separation reaction of multiply charged C z+60 ions into the two charged fragment ions C (z-1)+58 ...
We report tests performed on a microwave plasma ion source to determine its suitability for high sensitivity Kr and Xe isotopic analysis. The source consists of a 1.3 cm o.d. 15 cm long ceramic discharge tube with excitation provided by a 2.45 GHz λ cavity. We have developed a technique to generate 2 10 -11 A of Xe ions directly from air, with an ionization efficiency...
Low energy methyl glycolate radical cations , 1, abundantly lose HCO , yielding protonated methyl formate H-C(OH)OCH +3 . Tandem mass spectrometry based experiments on 2 H, 13 C and 18 O labelled isotopologues show that this loss is largely (about 75%) atom specific. Analysis of the atom connectivity in the product ions indicates that the reaction proceeds...
A Bi + ion emitter has been developed and studied which is modeled on the silica gel matrices that have been used to produce ions from a variety of elements such as Pb, Ag and Te for isotope ratio measurements. Studies with this model system demonstrate that this ion emitter is a liquid glass and that ion emission originates from the surface of the liquid glass. The large difference in ion...
Precise determinations of the isotopic compositions of molybdenum, tellurium, tin and tungsten were obtained utilizing an inductively coupled plasma (ICP) source magnetic sector mass spectrometer equipped with multiple collectors. The results of this study are comparable to those measured by conventional and negative thermal ionization mass spectrometry (TIMS and NTIMS) and the values recommended...
Results and experience are presented for a method of fractionation free measurements in thermal ionization mass spectrometery. The method can be used not only on multi-collector mass spectrometers, where the isotopes of interest can be measured simultaneously, but also on a thermal ionization quadrupole mass spectrometer using a special scanning and heating sequence. The total evaporation method...
A novel ceramic-like material has been produced and tested which has the property of emitting perrhenate anions for several thousand hours when heated in vacuum to temperatures between 1073 and 1173 K. Previously reported versions of this material were inferior to the material discussed here, probably owing to loss of perrhenate from reduction within the host matrix. The earlier materials, as well...
Glow discharge mass spectrometry (GDMS) has been evaluated for its ability to measure isotope ratios in solids. Isotope ratios were measured for B, Cu, Sr, Ag, Sb, Re and Pb in concentrations ranging from 15 ppm to pure metal. External precision of better than 0.03% has been achieved for isotope ratios measured using pure solid elemental samples; typical precision is better than 0.1% for elements...
The third-order trajectories of charged particles in crossed electric and magnetic fields have been calculated, and the results are expressed in the form of a transfer matrix. The differential equations are solved algebraically using the symbolic computation program Mathematica. The relativistic effects are taken into account. The transfer matrix elements can be expressed in both algebraic and...
Negative primary ions have an advantage for SIMS measurements when positive secondary ions are being observed, because they gain energy from the secondary ion accelerating voltage. Having both Cs + and I - ions available from the same ion source enables maximum bombarding energy to be obtained for both positive and negative secondary ion spectra without interrupting the vacuum.
An isotope dilution-thermal ionization mass spectrometry method for the determination of parts-per-million levels of iron in zirconium is required for precise, accurate analyses in studies of the effects of iron on the irradiation deformation of nuclear alloys. A two-stage purification procedure was developed to avoid the signal suppression and interference caused by the zirconium matrix. After...
Infrared multiphoton absorption is introduced as a method of direct heating of gas phase molecules prior to field ionization. This approach appears to be a very effective way to increase fragmentation following field ionization of the vibrationally excited molecules. Comparison is made with the method of electrical heating of the emitter which results in an indirect heating of the molecules prior...
Argides, dimers, and doubly charged metal ions were investigated as possible species to use for elemental quantification in glow discharge mass spectrometry. These species showed a behavior similar to that of the metal ion when discharge power was varied, and similar to that of the metal atom when discharge pressure was varied. Quantification of several National Institute of Standards and Technology...
From the inception of analytical mass spectrometry numerous efforts have been undertaken to minimize artifacts in mass spectra. While double-focusing techniques brought about significant progress in that interference signals in ion-source mass spectra can now be excluded, for MS/MS studies several kinds of artifacts exist when only two sectors are used in MS n (n 2) experiments. Tandem...
Simulations and experiments on the motion of collections of ions show that impulsive excitation, applied in the axial direction, forces ions into coherent motion with characteristic secular frequencies. A version of the ion trap simulation program, itsim, which accounts for the effects of ion/molecule collisions, is applied to show that this motion is remarkably stable even in the presence of bath...
Virtually all Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry experiments are based on ion confinement in a Penning trap: namely, a spatially homogeneous static magnetic field B, and a three-dimensional axial (along B) quadrupolar electrostatic trapping potential. In addition, it is desirable to provide an alternating azimuthal (i.e. in a plane perpendicular to B) spatially uniform...
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