Total Cross Sections for Ionization by Electron Impact

Harrison, Alex G.; Jones, Edwin; Gupta, S.; Nagy, Gabriella

doi:10.1139/v66-293

Cited by 96 publications

(106 citation statements)

References 7 publications

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“…This pressure is about a factor of 10 higher than was used for the exchange of the labile hydrogens of protonated aromatic amines (21) or protonated amino acids (24) with ND,. Since the ionization cross section is expected to be greatest for C2H50D and least for D20 (30), the use of the same indicated pressure means that the actual collision cell pressure was least for the alcohol and greatest for D20; despite the higher D20 pressure the exchange with D20 was the least efficient, as discussed below.…”

Section: Methodsmentioning

confidence: 99%

Reactive collisions in quadrupole cells. 6. H/D exchange reactions of protonated alkylbenzenes with D₂O, CH₃OD, and C₂H₅OD

Ni¹,

Harrison²

1995

Can. J. Chem.

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The H/D exchange reactions occurring on collision of protonated alkylbenzenes with C2H5OD, CH3OD, and D2O at low collision energies in the quadrupole collision cell of a hybrid tandem mass spectrometer have been studied for 22 alkylbenzenes. The exchange reactions with D2O are much less efficient than the exchange reactions with C2H5OD or CH3OD; this difference is rationalized on energetics grounds. The H/D exchange of the protonated alkylbenzenes with C2H5OD or CH3OD leads, typically, to 40–70% deuterium incorporation in the protonated alkylbenzene and, for most cases, to significant ion signals corresponding to exchange of the added hydrogen and the aromatic hydrogens. Thus, the method is a feasible approach to counting the number of aromatic hydrogens in alkylbenzenes. The extent of exchange decreases with increasing size of the alkyl group in monoalkylbenzenes for reasons that are not readily understood. Keywords: protonated alkylbenzenes, H/D exchange, reactive collisions.

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Section: Methodsmentioning

confidence: 99%

Reactive collisions in quadrupole cells. 6. H/D exchange reactions of protonated alkylbenzenes with D₂O, CH₃OD, and C₂H₅OD

Ni¹,

Harrison²

1995

Can. J. Chem.

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“…Figure 3 shows the relative sensitivity per unit mass of an AMS or similar instrument after accounting for the residence time in the ion source. The electron impact ionization cross-sections (circa 70 eV) are mostly from Harrison et al (1966). Some very light organics in Harrison et al that are not relevant to aerosols are not plotted; even the larger molecules available are generally smaller or less oxygenated than those relevant to ambient aerosol particles.…”

Section: Number Density In Free Molecular Flowmentioning

confidence: 99%

The effects of molecular weight and thermal decomposition on the sensitivity of a thermal desorption aerosol mass spectrometer

Murphy

2015

Aerosol Science and Technology

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In free molecular flow the slower speed of heavier molecules means that they spend more time in the ion source of a mass spectrometer. Hence the sensitivity of the thermal desorption mass spectrometers such as the Aerodyne Aerosol Mass Spectrometer (AMS) should include a term that scales as the square root of the molecular weight. Thermal decomposition on the vaporizer reduces the molecular weight prior to ionization and changes electron impact cross-sections. Thermal decomposition therefore has the potential to change the sensitivity, in some cases by more than a factor of three. Current AMS calibrations that rely upon an ammonium nitrate calibration and scaling for other components with a relative ionization efficiency may overestimate the concentration of large, thermally stable molecules and underestimate small or thermally unstable molecules. The overall sensitivity of the AMS to organics includes a partial cancellation of these effects. There is an incomplete understanding of the vaporization process, including that of ammonium nitrate.

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“…In spite of such important implications in ISM and other astrophysical environments, formates have not received much attention. Harrison et al [7] were the first to report the total ionization cross section for formates by 75 V electrons in 1966. Four decades later, Hudson et al [8] measured the absolute electron impact ionization cross sections of C 2 to C 6 formates and C 3 to C 7 acetates from 15 to 285 eV.…”

Section: Q2mentioning

confidence: 99%

Electron induced ionization cross sections for astrophysical modelling

Kaur

Antony

2015

International Journal of Mass Spectrometry

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Total Cross Sections for Ionization by Electron Impact

Cited by 96 publications

References 7 publications

Reactive collisions in quadrupole cells. 6. H/D exchange reactions of protonated alkylbenzenes with D₂O, CH₃OD, and C₂H₅OD

Reactive collisions in quadrupole cells. 6. H/D exchange reactions of protonated alkylbenzenes with D₂O, CH₃OD, and C₂H₅OD

The effects of molecular weight and thermal decomposition on the sensitivity of a thermal desorption aerosol mass spectrometer

Electron induced ionization cross sections for astrophysical modelling

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Total Cross Sections for Ionization by Electron Impact

Cited by 96 publications

References 7 publications

Reactive collisions in quadrupole cells. 6. H/D exchange reactions of protonated alkylbenzenes with D2O, CH3OD, and C2H5OD

Reactive collisions in quadrupole cells. 6. H/D exchange reactions of protonated alkylbenzenes with D2O, CH3OD, and C2H5OD

The effects of molecular weight and thermal decomposition on the sensitivity of a thermal desorption aerosol mass spectrometer

Electron induced ionization cross sections for astrophysical modelling

Contact Info

Product

Resources

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Reactive collisions in quadrupole cells. 6. H/D exchange reactions of protonated alkylbenzenes with D₂O, CH₃OD, and C₂H₅OD

Reactive collisions in quadrupole cells. 6. H/D exchange reactions of protonated alkylbenzenes with D₂O, CH₃OD, and C₂H₅OD