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An abundance sensitivity of < 10 ppb has been achieved with the redesigned retarding potential quadrupole (RPQ-II) on the Finnigan MAT 262 test instrument at the Finnigan MAT applications laboratory, and on the instrument installed at the Open University. The Open University instrument is equipped with a deflection unit after the RPQ-II to select a Faraday collector or a secondary electron multiplier...
Three-dimensional ion trajectories in Wien filters were calculated in a third-order approximation. The results were expressed as a total transfer matrix with aberration coefficients. Two-dimensional image shapes at an image plane were simulated by using these results. Focusing properties of the systems with a homogeneous Wien filter and a stigmatic Wien filter were investigated as examples. Third-order...
The development of a tandem mass spectrometric method, involving reactive collisions in a quadrupole collision cell, to study the reactions of metal ions with organic substrates is reported. This approach is evaluated by studying the reactions of singly charged transition metal ions with cyclopentene. The transition metal ions Sc + through Cu + were produced by fast atom bombardment...
The intent of this study was to determine the fraction of soluble uranium attributable to the Rocky Flats Plant (RFP) operations which is recoverable from waters and suspended sediments drawn from ponds on site at RFP. Samples were collected from late 1992 through 1993. Thermal ionization mass spectrometry (TIMS) measurement techniques indicate that the water samples contain both naturally occurring...
Proton-bound clusters of acetic acid and mixed clusters of acetic acid and water evaporate neutral dimers of acetic acid. This attribute is shared with liquid acetic acid. Clusters are considered to bridge the gap between the gas phase and condensed phases. The evaporation of dimers begins to be observed with the heptamer. Cluster binding energies to monomer and dimer units were deduced from kinetic...
A matrix-assisted laser desorption ionization (MALDI) source has been coupled to the ion chromatography instrument developed at UCSB. The source produces a strong, consistent signal for several hours on a single sample. In this paper we report the application of this method to a series of poly(ethylene glycol) (PEG) polymers cationized by sodium. Data have been taken for Na + PEG5 to Na...
Gas phase basicities for a series of N-alkylated peptides were found by the kinetic method using amines and guanidines as reference bases. The basicity value of one of these peptides was then remeasured using the rest of the derivatized peptides as reference bases. Both values appear to be in a good agreement. This suggests that structurally similar peptides (with unaltered topology of intramolecular...
The potential field in a dodecapole constellation is calculated for each of 12 standard potential distributions on the rods. These fields are represented by multipole series expansions. For multipoles with a different number of poles similar expressions are given.
The integrity of CANDU pressure tubes is critically dependent on the protectiveness of the oxide film formed on its surface. The actual protective layer may be only a few nanometres in thickness. In an on-going investigation of the properties of the protective oxide film, and the relationship of these properties to the corrosion behaviour of the pressure tubes, SIMS has become an important component...
Various gas-phase C 8 H 10 radical cations were investigated by using tandem mass spectrometry (MS/MS) and by utilizing AM1, PM3 and MNDO semi-empirical computations. The dissociation properties of the radical cations of bicyclo[2.2.2]octa-2,4-diene (dihydrobarrelene, DHB), bicyclo[4.2.0]octa-2,4-diene (BCO), 1,3,5-cyclooctatriene (COT), and 1,3,5,7-octatetraene (OT) were found...
The dynamics of the collision-induced dissociation of CS +2 molecular ions to CS + and S + fragment ions has been investigated using a crossed-beam tandem hybrid mass spectrometer at collision energies ranging from near threshold to 34.5 eV in the center-of-mass (CM) reference frame. The results show that small impact parameter impulsive collisions are involved in the...
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