Dissociative electron attachment to formamide

Szymańska, Ewelina; Nair, B G; Mason, Nigel J.; Krishnakumar, E.

doi:10.1088/1742-6596/388/5/052085

Cited by 3 publications

(3 citation statements)

References 5 publications

(4 reference statements)

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“…Electron attachment to FA can originate from a direct excitation event in FA and/or be assisted by the SiO 2 substrate. A possible reaction from the interaction with secondary electrons from an incident radiation, adopted from Hamann et al, is provided below: e − + HCONH 2 → ( HCONH 2 ) * − → OCN − + H 2 + H The thermodynamic threshold of this reaction is 2.2 eV in the gas phase . Our electron irradiation results suggest that H 2 production and H abstraction occur (data not shown) and that the heavy OCN – ion then remains trapped in the ice.…”

Section: Resultsmentioning

confidence: 68%

“…Additionally, condensed-phase DEA resonances can have larger cross-sections, shifted energies, and different branching ratios compared to the gas phase. Recent DEA resonances in FA ice have been observed to produce and desorb several anions including H – . Electron attachment to FA can originate from a direct excitation event in FA and/or be assisted by the SiO 2 substrate.…”

Section: Resultsmentioning

confidence: 99%

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Radiation Processing of Formamide and Formamide:Water Ices on Silicate Grain Analogue

2014

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Lyman-α (121.6 nm) photon and 1 keV electron-beam irradiation of pure HCONH2 (FA) ice and H2O:HCONH2 ice mixtures on high-surface-area SiO2 nanoparticles have been investigated with FT-IR spectroscopy and temperature programmed desorption (TPD). Lyman-α photolysis of pure amorphous FA ice grown at 70 K and crystalline FA ice produced by annealing to 165 K gives spectral signatures between 2120 and 2195 cm(-1) that we assign primarily to OCN(-) and CO. The OCN(-) and CO yields are ∼25% less abundant for crystalline FA ice. Photon and electron processing also produces H2 that is released from the ice between ∼90 and 140 K. A decrease in the H2 TPD peak is seen for irradiated crystalline HCONH2 ice. Lyman-α photolysis of H2O:HCONH2 mixed ices increases OCN(-) and CO production, suggesting a catalytic role of H2O. Also, for pure FA, 1 keV electron irradiation slightly increases the yield of OCN(-), while CO decarboxylation is selectively prevented. CO is also not produced in H2O:HCONH2 ices upon electron irradiation. Dissociative ionization, direct dissociative excitation, and dissociative electron attachment (DEA) channels are accessible in the Lyman-α (121.6 nm) photon and 1 keV electron-beam energy range. DEA energetically favors OCN(-) and H(-) formation, with the latter leading to H2 formation. The FA fragment product identities, yields, and branching ratios are considerably different relative to the gas phase and depend upon the radiation type, ice structure, and the presence of SiO2 nanoparticles. The latter may increase ion-electron recombination and radical recombination rates. The main products observed suggest very different condensed-phase dissociation channels from those reported for gas-phase dissociation. Formation of ions/products from FA is not negligible upon Lyman-α photolysis or electron irradiation, both of which could process ices in interstellar regions as well as in Titan's atmosphere.

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Section: Resultsmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 99%

Radiation Processing of Formamide and Formamide:Water Ices on Silicate Grain Analogue

2014

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“…Several of these reactions are expected to involve dissociative attachment by low energy secondary electrons. DEA to gaseous formamide has been studied previously, both theoretically [29][30][31] and experimentally [31][32][33]. Thus far, experimental probes of DEA to formamide have focused on fragment yields [32].…”

Section: Introductionmentioning

confidence: 99%

Investigating resonant low-energy electron attachment to formamide: dynamics of model peptide bond dissociation and other fragmentation channels

Panelli,

Moradmand,

Griffin

et al. 2020

Preprint

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We report experimental results on three-dimensional momentum imaging measurements of anions generated via dissociative electron attachment to gaseous formamide. From the momentum images, we analyze the angular and kinetic energy distributions for NH − 2 , O − , and H − fragments and discuss the possible electron attachment and dissociation mechanisms for multiple resonances for two ranges of incident electron energies, from 5.3 eV to 6.8 eV, and from 10.0 eV to 11.5 eV. Ab initio theoretical results for the angular distributions of the NH − 2 anion for ∼6 eV incident electrons, when compared with the experimental results, strongly suggest that one of the two resonances producing this fragment is a 2 A Feshbach resonance.

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Investigating resonant low-energy electron attachment to formamide: Dynamics of model peptide bond dissociation and other fragmentation channels

Panelli

Moradmand

Griffin

et al. 2021

Phys. Rev. Research

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Dissociative electron attachment to formamide

Cited by 3 publications

References 5 publications

Radiation Processing of Formamide and Formamide:Water Ices on Silicate Grain Analogue

Radiation Processing of Formamide and Formamide:Water Ices on Silicate Grain Analogue

Investigating resonant low-energy electron attachment to formamide: dynamics of model peptide bond dissociation and other fragmentation channels

Investigating resonant low-energy electron attachment to formamide: Dynamics of model peptide bond dissociation and other fragmentation channels

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