Nachweis von organischen Molekülkomplexen über deren negative Ionen

Abstract Molecular polymeres of organic compounds could be identified with a special mass spectrometer by their negative ions without fragmentation from acetone, methanol, and formic acid. Verification of these measurements was obtained by the investigation of deuterated samples. Molecular ions were measured up to trimers. Benzene and cyclohexane did not show polymer ions. The measured pressure dependence indicates preference of electron attachment in ion production against ion molecule reactions. The complexes are held together by the intermolecular dipole forces.

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Negative Ionen durch Elektronenstoß aus organischen Nitroverbindungen, Äthylnitrit und Äthylnitrat

Zeitschrift für Naturforschung A ◽

10.1515/zna-1967-0516 ◽

1967 ◽

Vol 22 (5) ◽

pp. 700-704

Author(s):

K. Jäger ◽

A. Henglein

Keyword(s):

Electron Impact ◽

Negative Ions ◽

Molecular Ions ◽

Ion Source ◽

Negative Ion ◽

Electron Affinities ◽

Low Intensity ◽

Ion Molecule Reactions ◽

Fragment Ions ◽

Product Ions

Negative ion formation by electron impact has been studied in nitromethane, nitroethane, nitrobenzene, tetranitromethane, ethylnitrite and ethylnitrate. Appearance potentials, ionization efficiency curves and kinetic energies of negative ions were measured by using a Fox ion source. The electron affinities of C2H5O and of C (NO2)3 are discussed as well as the energetics of processes which yield NO2-. The electron capture in nitrobenzene and tetranitromethane leads to molecular ions [C6H5NO2~ in high, C (NO2)4 in very low intensity] besides many fragment ions. A number of product ions from negative ion-molecule reactions has also been found.

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A novel rocket borne ion mass spectrometer with large mass range: instrument description and first flight results

10.5194/amt-2020-203 ◽

2020 ◽

Author(s):

Joan Stude ◽

Heinfried Aufmhoff ◽

Hans Schlager ◽

Markus Rapp ◽

Frank Arnold ◽

...

Keyword(s):

Mass Spectrometer ◽

Negative Ions ◽

Mass Range ◽

Large Mass ◽

Molecular Ions ◽

Negative Ion ◽

Cluster Ions ◽

The Arctic ◽

Atmospheric Species ◽

Smoke Particles

Abstract. We present a novel rocket borne ion mass spectrometer ROMARA (ROcket borne MAss spectrometer for Research in the Atmosphere) for measurements of atmospheric positive and negative ions (atomic, molecular and cluster ions) and positively and negatively charged meteor smoke particles. Our ROMARA instrument has, compared to previous rocket borne ion mass spectrometers, a markedly larger mass range of up to m/z 2000 and a larger sensitivity, particularly for meteor smoke particle detection. Mayor objectives of this first ROMARA flight included: a functional test of the ROMARA instrument, measurements between 55 km and 121 km in the mass range of atmospheric positive and negative ions, a first attempt to conduct mass spectrometric measurements in the mass range of meteor smoke particles with mass to charge ratios up to m/z 2000, and measurements inside a polar mesospheric winter echo layer as detected by ground based radar. Our ROMARA measurements took place on the Arctic island of Andøya/Norway around noon in April 2018 and represented an integral part of the PMWE rocket campaign. During the rocket flight, ROMARA was operated in a measurement mode, offering maximum sensitivity and the ability to qualitatively detect total ion signatures even beyond its mass resolving mass range. On this first ROMARA flight we were able to meet all of our objectives. We detected atmospheric species including positive atomic, molecular and cluster ions along with negative molecular ions up to about m/z 100. Above m/z 2000, ROMARA measured strong negative ion signatures, which are likely due to negatively charged meteor smoke particles.

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A novel rocket-borne ion mass spectrometer with large mass range: instrument description and first-flight results

Atmospheric Measurement Techniques ◽

10.5194/amt-14-983-2021 ◽

2021 ◽

Vol 14 (2) ◽

pp. 983-993

Author(s):

Joan Stude ◽

Heinfried Aufmhoff ◽

Hans Schlager ◽

Markus Rapp ◽

Frank Arnold ◽

...

Keyword(s):

Mass Spectrometer ◽

Negative Ions ◽

Mass Range ◽

Large Mass ◽

Molecular Ions ◽

Negative Ion ◽

Cluster Ions ◽

The Arctic ◽

Atmospheric Species ◽

Smoke Particles

Abstract. We present a novel rocket-borne ion mass spectrometer named ROMARA (ROcket-borne MAss spectrometer for Research in the Atmosphere) for measuring atmospheric positive and negative ions (atomic, molecular and cluster ions) and positively and negatively charged meteor smoke particles. Our ROMARA instrument has, compared to previous rocket-borne ion mass spectrometers, a markedly larger mass range of up to m/z 2000 and a larger sensitivity, particularly for meteor smoke particle detection. The major objectives of this first ROMARA flight included the following: a functional test of the ROMARA instrument, measurements between 55 and 121 km in the mass range of atmospheric positive and negative ions, a first attempt to conduct mass spectrometric measurements in the mass range of meteor smoke particles with mass-to-charge ratios up to m/z 2000, and measurements inside a polar mesospheric winter echo layer as detected by ground-based radar. Our ROMARA measurements took place on the Arctic island of Andøya, Norway, at around noon in April 2018 and represented an integral part of the polar mesospheric winter radar echo (PMWE) rocket campaign. During the rocket flight, ROMARA was operated in a measurement mode, offering maximum sensitivity and the ability to qualitatively detect total ion signatures even beyond its mass-resolving mass range. On this first ROMARA flight we were able to meet all of our objectives. We detected atmospheric species including positive atomic, molecular and cluster ions along with negative molecular ions up to about m/z 100. Above m/z 2000, ROMARA measured strong negative-ion signatures, which are likely due to negatively charged meteor smoke particles.

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Fragmentation pathways of negative ions produced by electrospray ionization of acyclic dicarboxylic acids and derivatives

Canadian Journal of Chemistry ◽

10.1139/v05-214 ◽

2005 ◽

Vol 83 (11) ◽

pp. 1878-1890 ◽

Cited By ~ 46

Author(s):

J Stuart Grossert ◽

Paul D Fancy ◽

Robert L White

Keyword(s):

Electrospray Ionization ◽

Mass Spectrometer ◽

Ion Trap ◽

Negative Ions ◽

Dicarboxylic Acids ◽

Negative Ion ◽

Triple Quadrupole Mass Spectrometer ◽

Fragmentation Pathways ◽

Ion Molecule Reactions ◽

Wide Range

Fragmentation pathways have been studied on the monoanions formed during electrospray ionization of a wide range of aliphatic dicarboxylic acids and their monoesters. All negative ion spectra were obtained from alcoholic or aqueous methanolic solutions without buffers or adjustment of pH, using either a Finnigan LCQ ion trap or a VG-Micromass Quattro triple quadrupole mass spectrometer. Fragmentation pathways were studied using collision-induced dissociation and isotopic-labelling techniques. Two primary fragmentation pathways of the dicarboxylic acid monoanions were observed, namely decarboxylation of the non-ionized carboxyl group and loss of water from this group. The fragmentations were strongly dependent on the chain lengths of the diacids. In the case of a monoester anion, loss of a molecule of alcohol paralleled the loss of water from the diacid monoanion. Losses of water or alcohol were shown to lead to formation of reactive ynolate anions (HOOC(CH2)xC≡CO, x = 39), which in the ion trap spectrometer engaged in complex ion molecule reactions consistent with the chemistry of these anions. For the longer chains (x > 6), the interactions between the ionized and non-ionized carboxyl groups led to readily formed ionneutral complexes, which are described as a neutral molecule (ROH, R = H or alkyl) held by a pair of molecular tweezers.Key words: ESI-MS/MS on negative ions, fragmentation pathways of acyclic carboxylic acid monoanions, ionmolecule reactions in an ion trap mass spectrometer, hydrogendeuterium exchange in a gas-phase anionneutral complex.

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Numerical Simulation of Leakage Current on Conductive Insulator Surface

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.d9759.118419 ◽

2019 ◽

Vol 8 (4) ◽

pp. 9487-9492

Keyword(s):

Numerical Simulation ◽

Electric Field ◽

Leakage Current ◽

Method Of Lines ◽

Electron Attachment ◽

Negative Ions ◽

Conduction Current ◽

Insulator Surface ◽

Finite Difference Approximations ◽

Positive Ions

The outdoor insulator is commonly exposed to environmental pollution. The presence of water like raindrops and dew on the contaminant surface can lead to surface degradation due to leakage current. However, the physical process of this phenomenon is not well understood. Hence, in this study we develop a mathematical model of leakage current on the outdoor insulator surface using the Nernst Planck theory which accounts for the charge transport between the electrodes (negative and positive electrode) and charge generation mechanism. Meanwhile the electric field obeys Poisson’s equation. Method of Lines technique is used to solve the model numerically in which it converts the PDE into a system of ODEs by Finite Difference Approximations. The numerical simulation compares reasonably well with the experimental conduction current. The findings from the simulation shows that the conduction current is affected by the electric field distribution and charge concentration. The rise of the conduction current is due to the distribution of positive ion while the dominancy of electron attachment with neutral molecule and recombination with positive ions has caused a significant reduction of electron and increment of negative ions.

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