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Wyniki wyszukiwania dla: DISSOCIATIVE ELECTRON ATTACHMENT
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Resonances and Dissociative Electron Attachment in HNCO
PublikacjaIn a combined experimental and theoretical study, we probe the dissociative electron attachment in isocyanic acid HNCO. The experimental absolute cross section for the NCO− fragment shows a sharp onset and fine structures near the threshold. The autoionizing state responsible for the dissociative attachment is found in both the R-matrix calculation and using analytic continuation in the coupling constant. The involved A' resonance...
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Dissociative electron attachment to benzoic acid (C7H6O2)
PublikacjaThe dissociative electron attachment (DEA) to benzoic acid (C6H5COOH) has been studied using an experimental crossed beam setup of a quadrupole mass spectrometer and a trochoidal electron monochromator. Relative partial cross sections for the DEA to produce negative ion fragments show the main channels for dissociation. The comparison of the present results with the ultraviolet photoelectron spectrum of benzoic acid [J. Meeks,...
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A Theoretical Model for Indirect Dissociative Electron Attachment
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Dissociative electron attachment of furan, tetrahydrofuran, and fructose
PublikacjaPrzeprowadzono badania wychwytu dysocjacyjnego elektronów w cząsteczkach furanu, tetrahydrofuranu i fruktozy w przedziale energii 0-14eV. Stwierdzono, że w przypadku wychwytu elektronów o energiach poniżej progu wzbudzenia (< 3eV), jedynie fruktoza jest podatna na rozerwanie pierścienia cukrowego. W cząsteczkach furanu i tetrahydrofuranu struktury rezonansowe odpowiadające fragmentom pierścienia pojawiają się dla energii elektronów...
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Dissociative electron attachment to the radiosensitizing chemotherapeutic agent hydroxyurea
PublikacjaDissociative electron attachment to hydroxyurea was studied in the gas phase for electron energies ranging from zero to 9 eV in order to probe its radiosensitizing capabilities. The experiments were carried out using a hemispherical electron monochromator coupled with a quadrupole mass spectrometer. Diversified fragmentation of hydroxyurea was observed upon low energy electron attachment and here we highlight the major dissociation...
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Temperature Dependence of the Dissociative Electron Attachment to 2-Thiothymine
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Dissociative electron attachment to HGaF4 Lewis–Brønsted superacid
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Electron collisions with cyanoacetylene HC3N : Vibrational excitation and dissociative electron attachment
PublikacjaWe experimentally probe electron collisions with HC3N in the energy range from 0 to 10 eV with the focus on vibrational excitation and dissociative electron attachment. The vibrational excitation cross sections show a number of resonances which are mode specific: the two dominant π∗ resonances are visible in the excitation of all the vibrational modes; however, broad σ ∗ resonances are visible only in certain bond-stretching vibrational...
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Dissociative electron attachment and anion-induced dimerization in pyruvic acid
PublikacjaWe report partial cross sections for the dissociative electron attachment to pyruvic acid. A rich fragmentation dynamics is observed. Electronic structure calculations facilitate the identification of complex rearrangement reactions that occur during the dissociation. Furthermore, a number of fragment anions produced at electron energies close to 0 eV are observed, that cannot originate from single electron-molecule collisions....
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Coulomb-Assisted Dissociative Electron Attachment: Application to a Model Peptide
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Dissociative electron attachment to gas phase thiothymine: experimental and theoretical approaches
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Ttotal dissociative electron attachment cross sections of selected amin acids
PublikacjaZaprezentowano całkowite przekroje czynne na dysocjacyjny wychwyt elektronów przez aminokwasy: glicynę, alaninę, prolinę, tryptofan oraz fenyloalaninę. Wartości przekrojów czynnych wyznaczono z pomiarów wydajności w produkcji jonów dodatnich oraz normalizację do całkowitych przekrojów czynnych na jonizację, obliczonych metodą BEB.
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Dissociative Electron Attachment to 5-Iodo-4-thio-2′-deoxyuridine: A Potential Radiosensitizer of Hypoxic Cells
PublikacjaIn the search for effective radiosensitizers for tumor cells, halogenated uracils have attracted more attention due to their large cross section for dissociation upon the attachment of low-energy electrons. In this study, we investigated dissociative electron attachment (DEA) to 5-iodo-4-thio-2'-deoxyuridine, a potential radiosensitizer using a crossed electron-molecule beam experiment coupled with quadrupole mass spectrometry....
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Electron-Induced Decomposition of 5-Bromo-4-thiouracil and 5-Bromo-4-thio-2′-deoxyuridine: The Effect of the Deoxyribose Moiety on Dissociative Electron Attachment
PublikacjaWhen modified uridine derivatives are incorporated into DNA, radical species may form that cause DNA damage. This category of molecules has been proposed as radiosensitizers and is currently being researched. Here, we study electron attachment to 5-bromo-4-thiouracil (BrSU), a uracil derivative, and 5-bromo-4-thio-20 -deoxyuridine (BrSdU), with an attached deoxyribose moiety via the N-glycosidic (N1-C) bond. Quadrupole mass spectrometry...
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Dissociative Low-Energy Electron Attachment to the C–S Bond of H3CSCH3 Influenced by Coulomb Stabilization
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Electron attachment to hexafluoropropylene oxide (HFPO)
PublikacjaWe probe the electron attachment in hexafluoropropylene oxide (HFPO), C3F6O, a gas widely used in plasma technologies. We determine the absolute electron attachment cross section using two completely different experimental approaches: (i) a crossed-beam experiment at single collision conditions (local pressures of 5 × 10−4 mbar) and (ii) a pulsed Townsend experiment at pressures of 20–100 mbar. In the latter method, the cross sections...
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ELECTRON ATTACHMENT TO HETEROGENEOUS MOLECULAR CLUSTERS
PublikacjaHeterogeneous clusters are unique model species enabling studies of bulk and surface processes by vacuum restricted methods. This is of particular importance for the reactions of low-energy electrons which have extremely short penetration depth in bulk environments. This contribution overviews our recent experiments with low-energy electrons and clusters prepared by different techniques. First, the deposition of molecules on argon...
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Dissociative excitation of carbon disulfide by electron impact.
PublikacjaZbadano wzbudzenie dysocjacyjne cząsteczek dwusiarczku węgla w zderzeniach z elektronami prowadzące do utworzenia rodników CS w stanie wzbudzonym A1Pi.Wyznaczono energię progu wzbudzenia dysocjacyjnego oraz obsadzenie poziomów oscylacyjnych v=0 i 1 rodnika CS.
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Electron ionization and low energy electron attachment to molecules of biological interest
PublikacjaEthylenediaminetetraacetic acid (EDTA) and 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS) were investigated by electron impact ionization and low energy electron attachment. Both compounds are components of biological buffers and often are used as DNA stabilizers in irradiation studies. hus it is of a great importance to understand their potential interactions with radiation. Our results revealed that at least one of them, EDTA, may...
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Electron ionization and low energy electron attachment to molecules of biological interest
PublikacjaEthylenediaminetetraacetic acid (EDTA) and 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS) were investigated by electron impact ionization and low energy electron attachment. Both compounds are components of biological buffers and often are used as DNA stabilizers in irradiation studies. hus it is of a great importance to understand their potential interactions with radiation. Our results revealed that at least one of them, EDTA, may...