The Electron Capture Detector and the Study of Reactions with Thermal Electrons

Chen, E. C. M.; Chen, E. S. D.

doi:10.1002/0471659894

Cited by 33 publications

(100 citation statements)

References 1 publication

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“…The number of orbitals used in the MCCI is varied to minimize the difference between the experiment and theory [10]. The CURES-EC procedures are computer experiments to determine whether, and to what accuracy, this is possible.…”

Section: Semi-empirical and Theoretical Cures-ec Methodsmentioning

confidence: 99%

“…The gas phase E a (AHC) were first determined using the electron capture detector (ECD) [3][4][5][6][7][8][9][10]. Since 1993, significantly different E a (AHC) for anthracene, pyrene, coronene, and tetracene have been measured by thermal charge transfer (TCT), dissociation of anion complexes, photodetachment, and photoelectron spectroscopy (PES) [8 -17].…”

Section: Introductionmentioning

confidence: 99%

“…Morse potentials have been calculated for single bond dissociations for these states [22][23][24][25][26][27][28][29]. The AE a of more than 80 aromatic hydrocarbons were accurately reproduced by the semi-empirical method referred to as "configuration interaction or unrestricted orbitals to relate experimental quantities to self-consistent field values by estimating electron correlation" (CURES-EC) in previous studies [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Electron affinities, gas phase acidities, and potential energy curves: Benzene

Jalbout

Trzaskowski

Chen

et al. 2006

Int J of Quantum Chemistry

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ABSTRACT:The experimental electron affinities of benzene, E a (Bz), 0.4 to Ϫ4.8 eV, are evaluated. Multiple negative ion states are proposed to account for different electron affinities. The semi-empirical procedure known as "configuration interaction or unrestricted orbitals to relate experimental quantities to self-consistent field values by estimating electron correlation" (CURES-EC) has several advantages: (i) supports multiple E a (Bz), (ii) supports the E a (phenyl) and the D(COH,Bz), (iii) supports the gas phase acidity of benzene from the latter, (iv) predicts the singlet-triplet split for the phenyl anion of 1.2(2) eV, and (v) predicts the existence of an excited quartet state of the benzene anion with an E a (Bz), Ϫ2.5(2) eV. Nine ionic Morse curves are calculated from CURES-EC properties and experimental data. These are compared with quantum mechanical crossing "c" potentials obtained using a subroutine in commercial software and ab initio and density functional theory (DFT) procedures. Curves are calculated for the proposed quartet state of the benzene anion.

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Section: Semi-empirical and Theoretical Cures-ec Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron affinities, gas phase acidities, and potential energy curves: Benzene

Jalbout

Trzaskowski

Chen

et al. 2006

Int J of Quantum Chemistry

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“…and Nitromethane are large only for thermal electrons [21]). Without losses to capture, these free electrons rapidly become sufficiently energetic to cause traditional Townsend avalanche multiplication.…”

Section: Carbon Disulfide (Cs 2 )mentioning

confidence: 99%

“…Collisional neutralization of CS 2 molecular ions in thermal equilibrium with CS 2 vapor could occur by inelastic ion-molecule collisions if the CM energy exceeded the 0.6 eV electron affinity [21] of CS 2 . If the drifting ions gain no energy on average from the drift field, such collisions could only occur if the field were so strong that an ion could gain kinetic energy from the field equal to twice the electron affinity, in one mean free path.…”

Section: Carbon Disulfide (Cs 2 )mentioning

confidence: 99%

On the mechanism of Townsend avalanche for negative molecular ions

Dion¹,

Martoff²,

Hosack³

2010

Astroparticle Physics

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Time projection chambers drifting negative ions (NITPC) instead of electrons have several advantages. A NITPC can operate at very high reduced drift fields without diffusion runaway, and the readout digitization sampling rate requirement is considerably relaxed due to the low drift speed of negative ions. The initiation of Townsend avalanches to allow gas gain in these devices has not been understood until now. It is shown here that the avalanche in low pressure CS 2 vapor is most likely initiated by collisional detachment of the electron from the negative molecular ion.In mixtures of Nitromethane vapor with CO 2 the mechanism appears to be more complex.

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Quantification and remote detection of nitro explosives by helium plasma ionization mass spectrometry (HePI‐MS) on a modified atmospheric pressure source designed for electrospray ionization

2012

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Helium Plasma Ionization (HePI) generates gaseous negative ions upon exposure of vapors emanating from organic nitro compounds. A simple adaptation converts any electrospray ionization source to a HePI source by passing helium through the sample delivery metal capillary held at a negative potential. Compared with the demands of other He-requiring ambient pressure ionization sources, the consumption of helium by the HePI source is minimal (20-30 ml/min). Quantification experiments conducted by exposing solid deposits to a HePI source revealed that 1 ng of 2,4,6-trinitrotoluene (TNT) on a filter paper (about 0.01 ng/mm(2)) could be detected by this method. When vapor emanating from a 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) sample was subjected to helium plasma ionization mass spectrometry (HePI-MS), a peak was observed at m/z 268 for (RDX●NO(2))(-). This facile formation of NO(2)(-) adducts was noted without the need of any extra additives as dopants. Quantitative evaluations showed RDX detection by HePI-MS to be linear over at least three orders of magnitude. TNT samples placed even 5 m away from the source were detected when the sample headspace vapor was swept by a stream of argon or nitrogen and delivered to the helium plasma ion source via a metal tube. Among the tubing materials investigated, stainless steel showed the best performance for sample delivery. A system with a copper tube, and air as the carrier gas, for example, failed to deliver any detectable amount of TNT to the source. In fact, passing over hot copper appears to be a practical way of removing TNT or other nitroaromatics from ambient air.

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The Electron Capture Detector and the Study of Reactions with Thermal Electrons

Cited by 33 publications

References 1 publication

Electron affinities, gas phase acidities, and potential energy curves: Benzene

Electron affinities, gas phase acidities, and potential energy curves: Benzene

On the mechanism of Townsend avalanche for negative molecular ions

Quantification and remote detection of nitro explosives by helium plasma ionization mass spectrometry (HePI‐MS) on a modified atmospheric pressure source designed for electrospray ionization

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