A PULSED ION SOURCE FOR THE STUDY OF UNIMOLECULAR AND BIMOLECULAR REACTIONS OF GAS-PHASE IONS

1965 ◽  
Vol 43 (1) ◽  
pp. 159-174 ◽  
Author(s):  
T. W. Shannon ◽  
F. Meyer ◽  
A. G. Harrison
Keyword(s):  
Reaction Time ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Rate Constant ◽  
Thermal Energy ◽  
Ion Source ◽  
Operating Characteristics ◽  
Bimolecular Reactions ◽  
Molecule Reaction ◽  
Gas Phase Ions

A pulsed ion source has been constructed for use with a magnetic-deflection mass spectrometer. With this source the time between ion formation and withdrawal for analysis can be controlled and varied in a known manner. The design and operating characteristics of the source are discussed and a technique is described for the measurement of ion withdrawal times using the pulsing technique. The rate constant for the ion molecule reaction[Formula: see text]has been determined for the reaction of thermal energy ions using reaction time as the experimental variable. The equivalent reactions in the deuteriomethanes have also been studied. Preliminary results obtained in the study of the unimolecular fragmentation of the cyclohexadiene, toluene, and spiroheptadiene parent ions are presented.

The gas phase reactivity of the dimethylchloronium ion with alkylbenzenes

1981 ◽  
Vol 59 (15) ◽  
pp. 2412-2416 ◽  
Author(s):  
John A. Stone ◽  
Margaret S. Lin ◽  
Jeffrey Varah
Keyword(s):  
High Pressure ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Aromatic Hydrocarbons ◽  
Relative Rate ◽  
Ion Source ◽  
Nucleophilic Displacement ◽  
Rate Of Reaction ◽  
Displacement Reactions ◽  
Bonded Complexes

The reactivity of the dimethylchloronium ion with a series of aromatic hydrocarbons has been studied in a high pressure mass spectrometer ion source using the technique of reactant ion monitoring. Benzene is unreactive but all others, from toluene to mesitylene, react by CH3+ transfer to yield σ-bonded complexes. The relative rate of reaction increases with increasing exothermicity in line with current theories of nucleophilic displacement reactions.

scholarly journals Ruthenium trisbipyridine as a candidate for gas-phase spectroscopic studies in a Fourier transform mass spectrometer

2004 ◽  
Vol 18 (2) ◽  
pp. 387-396 ◽  
Author(s):  
Jill R. Scott ◽  
Jason E. Ham ◽  
Bill Durham ◽  
Paul L. Tremblay
Keyword(s):  
Fourier Transform ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Rate Constant ◽  
Optical Detection ◽  
Sinapinic Acid ◽  
Spectroscopic Studies ◽  
Fluorescence Lifetimes ◽  
Fourier Transform Mass Spectrometer

Metal polypyridines are excellent candidates for gas-phase optical experiments where their intrinsic properties can be studied without complications due to the presence of solvent. The fluorescence lifetimes of [Ru(bpy)3]1+trapped in an optical detection cell within a Fourier transform mass spectrometer were obtained using matrix-assisted laser desorption/ionization to generate the ions with either 2,5-dihydroxybenzoic acid (DHB) or sinapinic acid (SA) as matrix. All transients acquired, whether using DHB or SA for ion generation, were best described as approximately exponential decays. The rate constant for transients derived using DHB as matrix was 4×107s−1, while the rate constant using SA was 1×107s−1. Some suggestions of multiple exponential decay were evident although limited by the quality of the signals. Photodissociation experiments revealed that [Ru(bpy)3]1+generated using DHB can decompose to [Ru(bpy)2]1+, whereas ions generated using SA showed no decomposition. Comparison of the mass spectra with the fluorescence lifetimes illustrates the promise of incorporating optical detection with trapped ion mass spectrometry techniques.

scholarly journals Reaction of active nitrogen with oxygen

1967 ◽  
Vol 45 (22) ◽  
pp. 2837-2840 ◽  
Author(s):  
A. S. Vlastaras ◽  
C. A. Winkler
Keyword(s):  
Reaction Time ◽  
Oxygen Atom ◽  
Gas Phase ◽  
Rate Constant ◽  
Analytical Method ◽  
Order Rate Constant ◽  
Maximum Amount ◽  
Active Nitrogen ◽  
Tube Reactor ◽  
Different Levels

The maximum yields of oxygen atoms, estimated at different levels in a long-tube reactor by gas-phase "titration" with NO2, were equal for the reactions of active nitrogen with NO and O2. In this reactor, the maximum oxygen-atom production from the oxygen reaction, determined by the amount of N2O3 produced with excess NO2, was found to correspond to the NO "titration" value for the active nitrogen and not to the maximum amount of HCN produced in the active nitrogen – ethylene reaction. A second-order rate constant, [Formula: see text] [Formula: see text]was obtained for the active nitrogen – oxygen reaction.Experiments in a short reactor showed that the validity of the analytical method based on the trapping of N2O3 depended upon adequate reaction time for the NO + NO2 reaction to occur.

scholarly journals Constraining the sensitivity of iodide adduct chemical ionization mass spectrometry to multifunctional organic molecules using the collision limit and thermodynamic stability of iodide ion adducts

2016 ◽  
Vol 9 (4) ◽  
pp. 1505-1512 ◽  
Author(s):  
Felipe D. Lopez-Hilfiker ◽  
Siddarth Iyer ◽  
Claudia Mohr ◽  
Ben H. Lee ◽  
Emma L. D'Ambro ◽  
...  
Keyword(s):  
Reaction Time ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Organic Molecules ◽  
Transmission Efficiency ◽  
Molecular Ions ◽  
Ionization Mass ◽  
Aerosol Composition ◽  
Molecule Reaction ◽  
Scanning Procedure

Abstract. The sensitivity of a chemical ionization mass spectrometer (ions formed per number density of analytes) is fundamentally limited by the collision frequency between reagent ions and analytes, known as the collision limit, the ion–molecule reaction time, and the transmission efficiency of product ions to the detector. We use the response of a time-of-flight chemical ionization mass spectrometer (ToF-CIMS) to N2O5, known to react with iodide at the collision limit, to constrain the combined effects of ion–molecule reaction time, which is strongly influenced by mixing and ion losses in the ion–molecule reaction drift tube. A mass spectrometric voltage scanning procedure elucidates the relative binding energies of the ion adducts, which influence the transmission efficiency of molecular ions through the electric fields within the vacuum chamber. Together, this information provides a critical constraint on the sensitivity of a ToF-CIMS towards a wide suite of routinely detected multifunctional organic molecules for which no calibration standards exist. We describe the scanning procedure and collision limit determination, and we show results from the application of these constraints to the measurement of organic aerosol composition at two different field locations.

CONCURRENT ION–MOLECULE REACTIONS IN ETHYLENE AND PROPYLENE

1963 ◽  
Vol 41 (2) ◽  
pp. 236-242 ◽  
Author(s):  
A. G. Harrison
Keyword(s):  
Field Strength ◽  
Mass Spectrometer ◽  
Cross Sections ◽  
High Pressures ◽  
Ion Source ◽  
Molecule Reaction ◽  
Ion Molecule Reactions ◽  
Secondary Ions ◽  
The Cross

The ion–molecule reactions occurring in ethylene and in propylene at high pressures in the mass spectrometer ion source have been studied. It has been shown that two of the six secondary ions in ethylene and four of the nine secondary ions studied in propylene are products of more than one ion–molecule reaction. The cross sections for the separate reactions at 10 v/cm field strength are reported.

scholarly journals Design of New Electrode Interface to Improve Transport of Atmospheric Pressure Ions into a Mass Spectrometer

2009 ◽  
Vol 6 (1) ◽  
pp. 39-46
Author(s):  
Francis Beaudry ◽  
Robert B. Moore
Keyword(s):  
Mass Spectrometer ◽  
Atmospheric Pressure ◽  
Ion Source ◽  
Mass Analyzer ◽  
Charged Droplets ◽  
Gas Phase Ions ◽  
New Apparatus ◽  
Electrode Interface ◽  
Transport Of Ions ◽  
Electrically Charged

An intermediate electrode was developed to improve the transfer of ions in atmospheric pressure from a first location, the ion source, to a second location, the mass spectrometer. The new apparatus increase the efficiency of mass analysis of molecular constituents of liquids, including trace analysis of chemical entities, in which an electrospray (ES) or IonSpray™ (IS) technique is used to produce electrically charged droplets which divide and evaporate to form gaseous ions of the molecular constituents. The gas phase ions are transported to the mass spectrometer by an electric field generated by a new electrode design that separates the two fundamental functions of an electrospray or an IonSpray™, which are the nebulization of charged droplets and the transport of ions into the mass analyzer. The results suggest that the new apparatus provide a gain in signal intensity up to 10 compared with the commercial product. A significant improvement in ion transport results in higher precision and accuracy and/or reduction of the amount of material needed for analysis.

Energy dependence of ion-molecule reactions. II. Methyl chloride

1969 ◽  
Vol 22 (11) ◽  
pp. 2275 ◽  
Author(s):  
NA McAskill
Keyword(s):  
Energy Range ◽  
Gas Phase ◽  
Energy Dependence ◽  
Mass Spectrometer ◽  
Rate Constant ◽  
Methyl Chloride ◽  
Negative Ion ◽  
Polar Molecules ◽  
Ion Energy ◽  
Ion Molecule Reactions

The ion-molecule reactions of ions in methyl chloride were studied in the gas phase at source pressures of up to 120 μ in a mass spectrometer using ions having exit energies which ranged from 0.2 to 2.0 eV. The ions produced by secondary processes included CH4Cl+, CH2Cl+, and C2H6Cl+. The rate constant for the reaction of CH3Cl+ was found to be independent of the ion energy in the energy range studied. A theoretical rate constant which is independent of the ion energy was also derived for reactions between ions and polar molecules. Negative ion spectra were briefly examined.

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