International Journal of Mass Spectrometry

Items from 1 to 20 out of 5,516 results

article

Chemical kinetics of yttrium ionization in H ₂ -O ₂ -N ₂ flames

ChenFeng QingFeng, John M. Goodings

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 1-12

Trace amounts (≤ 10 ^- ⁶ mol fraction) of yttrium were introduced into six H ₂ -O ₂ -N ₂ flames in the temperature range 1820-2400 K at atmospheric pressure. Metallic ions were observed by sampling the flames through a nozzle into a mass spectrometer, and were measured as profiles of ion concentration vs. distance (i.e. time) along the flame axis. The ions observed...

article

Ab initio calculations on the isomerization of the benzene radical cation to the Dewar benzene structure and on possible pathways for the formation of C ₄ H ₄ fragment ions from the benzene radical cation

W.J. van der Hart

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 23-38

Ab initio calculations of possible fragmentation pathways for the formation of C ₄ H ₄ fragment ions from the benzene radical cation show that the dissociation of lowest energy leads to the methylene cyclopropene radical cation. The calculated barriers for formation of the other classical C ₄ H ₄ ion structures, vinyl acetylene, cyclobutadiene, and butatriene, are...

article

Theoretical and mass spectrometric investigations of the formation of calcium fluoride cluster ions

R. Kaschner, J.S. Becker, G. Seifert

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 103-111

The formation of Ca _n F ⁺ _m cluster ions (n = 1-3, m = 1-4) was investigated by using two different plasma mass spectrometric methods: spark source mass spectrometry and laser ablation inductively coupled plasma mass spectrometry. Both methods give similar abundance distributions of cluster ions, with a maximum ion intensity for the Ca ₂ F ⁺ ₃ species. These...

article

Matrix-assisted laser desorption/chemical ionization with reagent ion generation directly from a liquid matrix

K. Breuker, R. Knochenmuss, R. Zenobi

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 149-159

Highly concentrated aqueous salt solutions were tested for their ability to serve as a reagent anion source for matrix-assisted laser desorption/chemical ionization (MALD/Cl). It was found that tetrabutylammonium salt/silicon binary matrices yielded abundant deprotonated analyte signals. Moreover, controlled, specific fragmentation of carbohydrates, nucleotides, and peptides was observed, providing...

article

Multiphoton ionization mass spectrometry of small biomolecules with nanosecond and femtosecond laser pulses

N.P. Lockyer, J.C. Vickerman

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 77-86

This paper reports on the multiphoton ionization and dissociation (MPID) processes that occur in gas phase dipeptides excited with femtosecond and nanosecond laser pulses. The MPID products of the compounds tyrosyl-tyrosine, tyrosyl-leucine, and valyl-valine resulting from excitation with 5 ns and 250 fs laser pulses at 266 nm have been analysed by time-of-flight mass spectrometry. There are two...

article

Relationship between effective temperature of thermalized ions and ion source temperature

K. Norrman, T.B. McMahon

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 87-97

The spontaneous dissociation of mixed proton bound dimers of nitrile bases has been studied using mass-analyzed ion kinetic energy spectra in a reverse geometry double focusing instrument coupled to a high pressure ion source. A linear correlation was found between the relative ion abundance ratios of the fragments and the ion source temperature. Proton exchange equilibria between the bases were...

article

Rapid mass spectrometric determination of preferred irreversible proteinase inhibitors in combinatorial libraries

John E. Mckendrick, Sven Frormann, Colin Luo, Paul Semchuck, more

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 113-124

Optimal N-iodoacetyldipeptide inactivators of hepatitis A virus 3C proteinase were identified directly from equimolar mixtures of these compounds using electrospray ionization mass spectrometry (ESI-MS). Limiting amounts of proteinase were allowed to react with the library of inhibitors and subsequently analyzed by ESI-MS to determine the mass of the adducts formed. N-iodoacetyl-Ser-Phe-NH ₂...

article

Details of the measurement of rare earth and other trace element abundances by secondary ion mass spectrometry

A.J. Fahey

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 63-76

Details of a method for quantitative measurement of rare earth element (REE) abundances by secondary ion mass spectrometry are presented. The specifics of the multipass deconvolution algorithm are given. Direct measurements of the ratios of REE to REE oxide ion signals (η _i ) as a function of energy are shown and investigated. The η _i are important quantities used to determine the...

article

Complexation of polyethers and pyridyl ligands with monopositive transition metal ions in the gas phase

Jim Shen, Jennifer S. Brodbelt

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 39-61

The formation, ligand exchange reactions, and dissociation of various types of mixed ligand/metal complexes are studied in a quadrupole ion trap. The monopositive complexes are generated by ion-molecule association reactions between the polydentate organic ligands and laser-desorbed monopositive metal ions (M ⁺ ) and incorporate at least one polyether or at least one pyridyl ligand bound...

article

Sputter induced topography on silver coated silicon nitride ceramics by unfocused neutral primary beam selected ion mass spectrometry

W. Dümmler, S. Weber, N. Maloufi, C. Tête, more

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 125-131

In a specially modified apparatus for secondary ion mass spectrometry, silver-coated and uncoated silicon nitride ceramics were sputtered by means of unfocused neutral particle bombardment. The roughnesses of the obtained craters were measured by atomic force microscopy, in order to examine changes of the surface topography as a function of eroded depth. The unfocused neutral particle bombardment...

article

Static multicollection of Cs ₂ BO ⁺ ₂ ions for precise boron isotope analysis with positive thermal ionization mass spectrometry

Toshio Nakano, Eizo Nakamura

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 13-21

Static multicollection of Cs ₂ BO ⁺ ₂ ions (m/z = 308 and 309) for precise boron isotope analysis has been established by employing a newly developed double collector package in the modified Finnigan-MAT 261 thermal ionization mass spectrometer (TIMS). This method reduces the data acquisition time to 5 min which is approximately one order of magnitude shorter than conventional...

article

Resolving power enhancement of a discrete detector (array) by single event detection

M.P. Sinha, D.P. Langstaff, D.J. Narayan, K. Birkinshaw

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 99-102

Experiments have been performed to demonstrate the high resolving power of a discrete detector array that can be achieved by measuring and processing single ion events (speckle mode). Measurement of the spectrum of Kr ⁺ using a miniature mass spectrometer developed at the jet propulsion laboratory equipped with a focal plane detector developed at Aberystwyth show a large resolving power enhancement...

article

Fractionation correction and multiple collectors in thermal ionization isotope ratio mass spectrometry

K. Habfast

International Journal of Mass Spectrometry > 1998 > 176 > 1-2 > 133-148

A comprehensive theory for the correction of time- and mass-dependent evaporation-related mass fractionation effects is developed. The Rayleigh distillation equation and the Langmuir equation describing evaporation are combined and are formulated here as the Rayleigh-Langmuir fractionation model, which provides the only currently available fundamental or causal description of evaporation...

article

Laser induced vaporization mass spectrometric studies on Si ₃ N ₄

M. Joseph, N. Sivakumar, P. Manoravi

International Journal of Mass Spectrometry > 1998 > 176 > 3 > 237-244

An Si ₃ N ₄ sample was irradiated with an Nd-YAG laser. The species present in the plume were detected by a quadrupole mass spectrometer (QMS). The species observed were Si, SiN, Si ₂ , Si ₂ N, Si ₃ , Si ₃ N, Si ₄ , Si ₃ N ₄ , Si ₆ , Si ₇ , and N. Weak signals were observed at m/e = 126 and 280. The analysis of...

article

Selected ion flow tube studies of the reactions of H ₃ O ⁺ , NO ⁺ , and O ₂ ⁺ with some organosulphur molecules

Patrik Španěl, David Smith

International Journal of Mass Spectrometry > 1998 > 176 > 3 > 167-176

We report the results of a selected ion flow tube (SIFT) study of the reactions of H ₃ O ⁺ , NO ⁺ , and O ₂ ⁺ with eight organosulphur molecules, M. If we assume that all the exothermic proton transfer reactions of H ₃ O ⁺ occur at the collision rate (i.e. the rate coefficients, k, are equal to the collisional rate coefficient, k _c ), it...

article

Application of ab initio direct dynamics calculations on the ionization and electron attachment processes for the CCl ₃ F molecule

Toshiyuki Takayanagi, Yuzuru Kurosaki, Hiroto Tachikawa

International Journal of Mass Spectrometry > 1998 > 176 > 3 > 227-235

Ab initio direct dynamics calculations have been carried out for the ionization and electron attachment processes for the CCl ₃ F molecule in order to obtain dynamical information on these processes. CCl ₃ F ⁺ produced via vertical ionization directly dissociates into CCl ₂ F ⁺ + Cl within a very short time. It has been found that 80% of the available energy...

article

Microchannel plate electron multiplier calibration using a discrete detector array

D.J. Narayan, D.P. Langstaff, M.P. Sinha, K. Birkinshaw

International Journal of Mass Spectrometry > 1998 > 176 > 3 > 161-166

The performance of a microchannel plate electron multiplier (MCP) is known to vary with time and exposure to ions, the atmosphere, and other factors. Clearly the recognition of deterioration in experimental work is of great importance. In the present work the performance of an MCP is straightforwardly measured using a detector array integrated on a silicon chip and results presented. The objective...

article

Negative ionization processes of osmium for isotopic measurements

Kéiko Hattori, T. James S. Cole, Douglas P. Menagh

International Journal of Mass Spectrometry > 1998 > 176 > 3 > 189-201

Negative ion mass spectrometry (N-TIMS) for many elements requires O ₂ gas, thermal electrons, and hot filament temperatures. These requirements are partly in conflict. For example, O ₂ , essential for volatilization of refractory metals, has _p oisoning effects on electron emission. Hot filament temperatures enhance reactions, but greater thermal electron emission...

article

Absolute total and partial electron impact ionization cross sections of hexamethyldisiloxane

R. Basner, R. Foest, M. Schmidt, K. Becker, more

International Journal of Mass Spectrometry > 1998 > 176 > 3 > 245-252

We studied the electron impact ionization of hexamethyldisiloxane (HMDSO), Si ₂ O(CH ₃ ) ₆ , which is widely used in plasma-enhanced polymerization applications. Appearance energies and absolute partial cross sections for the formation of fragment ions with relative intensities >1% of the most abundant ion, the Si ₂ O(CH ₃ ) ₅ ⁺ fragment ion,...

article

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International Journal of Mass Spectrometry > 1998 > 176 > 3 > 255-258

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Keywords

MASS SPECTROMETRY (439)
ELECTROSPRAY IONIZATION (135)
TANDEM MASS SPECTROMETRY (127)
COLLISION-INDUCED DISSOCIATION (114)
MALDI (105)
ELECTROSPRAY (92)
FRAGMENTATION (81)
QUADRUPOLE ION TRAP (77)
AB INITIO CALCULATIONS (67)
DENSITY FUNCTIONAL THEORY (66)
ION MOBILITY (64)
ION-MOLECULE REACTIONS (63)
PROTON TRANSFER (63)
ION MOBILITY SPECTROMETRY (60)
FT-ICR (59)
PTR-MS (57)
TIME-OF-FLIGHT (55)
PENNING TRAP (54)
ION TRAP (53)
DISSOCIATIVE ELECTRON ATTACHMENT (52)
PROTON AFFINITY (50)
CHEMICAL IONIZATION (48)
ELECTRON ATTACHMENT (47)
PHOTODISSOCIATION (46)
CLUSTERS (44)
FTMS (44)
CHARGE TRANSFER (43)
CID (43)
IONIZATION (43)
TIME-OF-FLIGHT MASS SPECTROMETRY (42)
CLUSTER (41)
PHOTOIONIZATION (41)
ION/MOLECULE REACTIONS (40)
SECONDARY ION MASS SPECTROMETRY (40)
THERMOCHEMISTRY (40)
SIFT (39)
KINETIC METHOD (37)
COLLISION INDUCED DISSOCIATION (36)
ESI (36)
KINETICS (36)
ELECTRON IONIZATION (34)
NEGATIVE IONS (34)
TIMS (34)
AMINO ACIDS (33)
IRMPD (33)
MS/MS (33)
AB INITIO (32)
ELECTRON IMPACT (32)
ELECTRON TRANSFER (32)
ION TRAP MASS SPECTROMETRY (32)
PROTEOMICS (32)
ELECTRON IMPACT IONIZATION (31)
GAS PHASE (31)
PEPTIDES (31)
ELECTRON CAPTURE DISSOCIATION (30)
ESI-MS (30)
CLUSTER IONS (29)
DFT (29)
DFT CALCULATIONS (29)
ION-MOLECULE REACTION (29)
PEPTIDE (29)
LASER ABLATION (28)
REACTION MECHANISM (28)
ELECTRON AFFINITY (27)
H/D EXCHANGE (27)
ICP-MS (26)
ION CYCLOTRON RESONANCE (26)
KINETIC ENERGY RELEASE (26)
SIMS (26)
DISSOCIATION (25)
ELECTRON TRANSFER DISSOCIATION (25)
SURFACE-INDUCED DISSOCIATION (25)
VOLATILE ORGANIC COMPOUNDS (25)
CROSS SECTIONS (24)
FTICR (24)
FULLERENES (24)
PEPTIDE FRAGMENTATION (24)
URANIUM (23)
COLLISIONAL ACTIVATION (22)
COULOMB EXPLOSION (22)
DICATION (22)
ELECTROSPRAY IONIZATION MASS SPECTROMETRY (22)
ION–MOLECULE REACTION (22)
ION–MOLECULE REACTIONS (22)
FLOWING AFTERGLOW (21)
FRAGMENTATION MECHANISM (21)
INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY (21)
IONIZATION ENERGY (21)
IRMPD SPECTROSCOPY (21)
SIFT-MS (21)
INFRARED SPECTROSCOPY (20)
MULTIPLY CHARGED IONS (20)
THERMAL IONIZATION MASS SPECTROMETRY (20)
DFT CALCULATION (19)
TOF-SIMS (19)
BOND DISSOCIATION ENERGIES (18)
ION/MOLECULE REACTION (18)
METAL CLUSTERS (18)
QUANTIFICATION (18)
CATALYSIS (17)
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INFONA - science communication portal

International Journal of Mass Spectrometry

Chemical kinetics of yttrium ionization in H ₂ -O ₂ -N ₂ flames

Ab initio calculations on the isomerization of the benzene radical cation to the Dewar benzene structure and on possible pathways for the formation of C ₄ H ₄ fragment ions from the benzene radical cation

Theoretical and mass spectrometric investigations of the formation of calcium fluoride cluster ions

Matrix-assisted laser desorption/chemical ionization with reagent ion generation directly from a liquid matrix

Multiphoton ionization mass spectrometry of small biomolecules with nanosecond and femtosecond laser pulses

Relationship between effective temperature of thermalized ions and ion source temperature

Rapid mass spectrometric determination of preferred irreversible proteinase inhibitors in combinatorial libraries

Details of the measurement of rare earth and other trace element abundances by secondary ion mass spectrometry

Complexation of polyethers and pyridyl ligands with monopositive transition metal ions in the gas phase

Sputter induced topography on silver coated silicon nitride ceramics by unfocused neutral primary beam selected ion mass spectrometry

Static multicollection of Cs ₂ BO ⁺ ₂ ions for precise boron isotope analysis with positive thermal ionization mass spectrometry

Resolving power enhancement of a discrete detector (array) by single event detection

Fractionation correction and multiple collectors in thermal ionization isotope ratio mass spectrometry

Laser induced vaporization mass spectrometric studies on Si ₃ N ₄

Selected ion flow tube studies of the reactions of H ₃ O ⁺ , NO ⁺ , and O ₂ ⁺ with some organosulphur molecules

Application of ab initio direct dynamics calculations on the ionization and electron attachment processes for the CCl ₃ F molecule

Microchannel plate electron multiplier calibration using a discrete detector array

Negative ionization processes of osmium for isotopic measurements

Absolute total and partial electron impact ionization cross sections of hexamethyldisiloxane

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