Fragmentation and Ion Desorption from Condensed Pyrimidine by Electron Impact: Implications for Cometary and Interstellar Heterocyclic Chemistry

Ribeiro, Fabio de A.; Almeida, Guilherme C.; Wolff, W.; Boechat-Roberty, H. M.; Rocco, Maria Luiza M.

doi:10.1021/jp504464w

Cited by 11 publications

(3 citation statements)

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“…More details about the available experimental setup can be found elsewhere. 33 The positive ion desorption yield Y i (ions/electron) for each desorbed ion was derived directly from the time-of-flight (TOF) mass spectrum by the standard expression: 33,34…”

Section: Methodsmentioning

confidence: 99%

Non-thermal ion desorption from an acetonitrile (CH₃CN) astrophysical ice analogue studied by electron stimulated ion desorption

Ribeiro

Almeida

Garcia-Basabe

et al. 2015

Phys. Chem. Chem. Phys.

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The incidence of high-energy radiation onto icy surfaces constitutes an important route for leading new neutral or ionized molecular species back to the gas phase in interstellar and circumstellar environments, especially where thermal desorption is negligible. In order to simulate such processes, an acetonitrile ice (CH3CN) frozen at 120 K is bombarded by high energy electrons, and the desorbing positive ions are analyzed by time-of-flight mass spectrometry (TOF-MS). Several fragment and cluster ions were identified, including the Hn=1-3(+), CHn=0-3(+)/NHn=0-1(+); C2Hn=0-3(+)/CHn=0-3N(+), C2Hn=0-6N(+) ion series and the ion clusters (CH3CN)n=1-2(+) and (CH3CN)n=1-2H(+). The energy dependence on the positive ion desorption yield indicates that ion desorption is initiated by Coulomb explosion following Auger electronic decay. The results presented here suggest that non-thermal desorption processes, such as desorption induced by electronic transitions (DIET) may be responsible for delivering neutral and ionic fragments from simple nitrile-bearing ices to the gas-phase, contributing to the production of more complex molecules. The derived desorption yields per electron impact may contribute to chemical evolution models in different cold astrophysical objects, especially where the abundance of CH3CN is expected to be high.

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Section: Methodsmentioning

confidence: 99%

Non-thermal ion desorption from an acetonitrile (CH₃CN) astrophysical ice analogue studied by electron stimulated ion desorption

Ribeiro

Almeida

Garcia-Basabe

et al. 2015

Phys. Chem. Chem. Phys.

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“…The interaction of radiation with biomolecules in the gas phase has gained attention in recent years since the radiation-induced electronic and nuclear dynamics often lead to fragmentation of the molecule. The microscopic picture of such dynamics of radiation damages in biomolecules is a pivotal piece of information in the field of biology, biotechnology, astrochemistry, and astrobiology. − Proteins are biomolecules that drive many of the biochemical processes of life, and the functioning of a protein is governed by its structure. Protein molecules are large polymers built up by amino acids, and deciphering the radiation-induced electron dynamics in a protein molecule with a complicated structure is quite challenging.…”

Section: Introductionmentioning

confidence: 99%

X-ray Induced Fragmentation of Protonated Cystine

et al. 2022

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We demonstrate site-specific X-ray induced fragmentation across the sulfur L-edge of protonated cystine, the dimer of the amino acid cysteine. Ion yield NEXAFS were performed in the gas phase using electrospray ionization (ESI) in combination with an ion trap. The interpretation of the sulfur L-edge NEXAFS spectrum is supported by Restricted Open-Shell Configuration Interaction (ROCIS) calculations. The fragmentation pathway of triply charged cystine ions was modeled by Molecular Dynamics (MD) simulations. We have deduced a possible pathway of fragmentation upon excitation and ionization of S 2p electrons. The disulfide bridge breaks for resonant excitation at lower photon energies but remains intact upon higher energy resonant excitation and upon ionization of S 2p. The larger fragments initially formed subsequently break into smaller fragments.

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“…In this way, new processed molecules, ions, and molecular clusters can be formed, resulting in a complex chemical environment. Several spectroscopic studies have been done in order to understand the dynamics of excited states, ionization, and dissociation of acetonitrile. − In addition, some experimental studies simulate the astrophysical environments aiming at investigating possible fragmentation and formation routes of more complex species. − …”

Section: Introductionmentioning

confidence: 99%

Structure, Stability, and Spectroscopic Properties of Small Acetonitrile Cation Clusters

et al. 2020

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Ionization and fragmentation pathways induced by ionizing agents are key to understanding the formation of complex molecules in astrophysical environments. Acetonitrile (CH 3 CN), the simplest organic nitrile, is an important molecule present in the interstellar medium. In this work, DFT and MP2 calculations were performed in order to obtain the low energy structures of the most relevant cations formed from electron-stimulated ion desorption of CH 3 CN ices. Selected reaction pathways and spectroscopic properties were also calculated. Our results indicate that the most stable acetonitrile cation structure is CH 2 CNH + and that hydrogenation can occur successively without isomerization steps until its complete saturation. Moreover, the stability of distinct cluster families formed from the interaction of acetonitrile with small fragments, such as CH n + , C 2 H n + , and CH n CNH + , is discussed in terms of their respective binding energies. Some of these molecular clusters are stabilized by hydrogen bonds, leading to species whose infrared features are characterized by a strong redshift of the N− H stretching mode. Finally, the rotational spectra of CH 3 CN and protonated acetonitrile, CH 3 CNH + , were simulated using distinct computational protocols based on DFT, MP2, and CCSD(T) considering centrifugal distortion, vibrational−rotational coupling, and vibrational anharmonicity corrections. By adopting an empirical scaling procedure for calculating spectroscopic parameters, we were able to estimate the rotational frequencies of CH 3 CNH + with an expected average error below 1 MHz for J values up to 10.

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Fragmentation and Ion Desorption from Condensed Pyrimidine by Electron Impact: Implications for Cometary and Interstellar Heterocyclic Chemistry

Cited by 11 publications

References 50 publications

Non-thermal ion desorption from an acetonitrile (CH₃CN) astrophysical ice analogue studied by electron stimulated ion desorption

Non-thermal ion desorption from an acetonitrile (CH₃CN) astrophysical ice analogue studied by electron stimulated ion desorption

X-ray Induced Fragmentation of Protonated Cystine

Structure, Stability, and Spectroscopic Properties of Small Acetonitrile Cation Clusters

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Fragmentation and Ion Desorption from Condensed Pyrimidine by Electron Impact: Implications for Cometary and Interstellar Heterocyclic Chemistry

Cited by 11 publications

References 50 publications

Non-thermal ion desorption from an acetonitrile (CH3CN) astrophysical ice analogue studied by electron stimulated ion desorption

Non-thermal ion desorption from an acetonitrile (CH3CN) astrophysical ice analogue studied by electron stimulated ion desorption

X-ray Induced Fragmentation of Protonated Cystine

Structure, Stability, and Spectroscopic Properties of Small Acetonitrile Cation Clusters

Contact Info

Product

Resources

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Non-thermal ion desorption from an acetonitrile (CH₃CN) astrophysical ice analogue studied by electron stimulated ion desorption

Non-thermal ion desorption from an acetonitrile (CH₃CN) astrophysical ice analogue studied by electron stimulated ion desorption