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Cerqueira HBA, Santos JC, Fantuzzi F, Ribeiro FDA, Rocco MLM, Oliveira RR, Rocha AB. Structure, Stability, and Spectroscopic Properties of Small Acetonitrile Cation Clusters. J Phys Chem A 2020; 124:6845-6855. [PMID: 32702984 DOI: 10.1021/acs.jpca.0c03529] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ionization and fragmentation pathways induced by ionizing agents are key to understanding the formation of complex molecules in astrophysical environments. Acetonitrile (CH3CN), 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 CH3CN ices. Selected reaction pathways and spectroscopic properties were also calculated. Our results indicate that the most stable acetonitrile cation structure is CH2CNH+ 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 CHn+, C2Hn+, and CHnCNH+, 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 CH3CN and protonated acetonitrile, CH3CNH+, 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 CH3CNH+ with an expected average error below 1 MHz for J values up to 10.
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Affiliation(s)
- Henrique B A Cerqueira
- Instituto de Quı́mica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil
| | - Julia C Santos
- Instituto de Quı́mica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil
| | - Felipe Fantuzzi
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.,Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Straße 42, 97074 Würzburg, Germany
| | | | - Maria Luiza M Rocco
- Instituto de Quı́mica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil
| | - Ricardo R Oliveira
- Instituto de Quı́mica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil
| | - Alexandre B Rocha
- Instituto de Quı́mica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil
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Abstract
Recent observational studies of intermediate- and high-mass star-forming regions at submillimeter and infrared wavelengths are reviewed, and chemical diagnostics of the different physical components associated with young stellar objects are summarized. Procedures for determining the temperature, density and abundance profiles in the envelopes are outlined. A detailed study of a set of infrared-bright massive young stars reveals systematic increases in the gas/solid ratios, the abundances of evaporated molecules, and the fraction of heated ices with increasing temperature. Since these diverse phenomena involve a range of temperatures from < 100 K to 1000 K, the enhanced temperatures must be communicated to both the inner and outer parts of the envelopes. This ‘global heating’ plausibly results from the gradual dispersion of the envelopes with time. Similarities and differences with low-mass YSOs are discussed. The availability of accurate physical models will allow chemical models of ice evaporation followed by ‘hot core’ chemistry to be tested in detail.
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Ribeiro FDA, Almeida GC, Garcia-Basabe Y, Wolff W, Boechat-Roberty HM, Rocco MLM. Non-thermal ion desorption from an acetonitrile (CH3CN) astrophysical ice analogue studied by electron stimulated ion desorption. Phys Chem Chem Phys 2015; 17:27473-80. [DOI: 10.1039/c5cp05040e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Non-thermal desorption by electron impact constitutes an important route by which neutral and ionic fragments from simple nitrile-bearing ices may be delivered back to the gas-phase of astrophysical environments, contributing to the production of more complex molecules.
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Affiliation(s)
- F. de A. Ribeiro
- Instituto de Química
- Universidade Federal do Rio de Janeiro
- Rio de Janeiro
- Brazil
- Instituto Federal de Educação
| | - G. C. Almeida
- Instituto de Química
- Universidade Federal do Rio de Janeiro
- Rio de Janeiro
- Brazil
- Departamento de Física
| | - Y. Garcia-Basabe
- Instituto de Química
- Universidade Federal do Rio de Janeiro
- Rio de Janeiro
- Brazil
- Instituto Latino-Americano de Ciências da Vida e da Natureza
| | - W. Wolff
- Instituto de Física
- Universidade Federal do Rio de Janeiro
- Rio de Janeiro
- Brazil
| | | | - M. L. M. Rocco
- Instituto de Química
- Universidade Federal do Rio de Janeiro
- Rio de Janeiro
- Brazil
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Rimola A, Sodupe M, Ugliengo P. Deep-space glycine formation via Strecker-type reactions activated by ice water dust mantles. A computational approach. Phys Chem Chem Phys 2010; 12:5285-94. [DOI: 10.1039/b923439j] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Mori T, Suma K, Sumiyoshi Y, Endo Y. Spectroscopic detection of isolated carbonic acid. J Chem Phys 2009; 130:204308. [DOI: 10.1063/1.3141405] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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Manca C, Martin C, Allouche A, Roubin P. Experimental and Theoretical Reinvestigation of CO Adsorption on Amorphous Ice. J Phys Chem B 2001. [DOI: 10.1021/jp013100f] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C. Manca
- Physique des Interactions Ioniques et Moléculaires UMR 6633, Université de Provence, Centre Saint Jérôme (case 242), 13397 Marseille Cedex 20, France
| | - C. Martin
- Physique des Interactions Ioniques et Moléculaires UMR 6633, Université de Provence, Centre Saint Jérôme (case 242), 13397 Marseille Cedex 20, France
| | - A. Allouche
- Physique des Interactions Ioniques et Moléculaires UMR 6633, Université de Provence, Centre Saint Jérôme (case 242), 13397 Marseille Cedex 20, France
| | - P. Roubin
- Physique des Interactions Ioniques et Moléculaires UMR 6633, Université de Provence, Centre Saint Jérôme (case 242), 13397 Marseille Cedex 20, France
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Manca C, Allouche A. Quantum study of the adsorption of small molecules on ice: The infrared frequency of the surface hydroxyl group and the vibrational stark effect. J Chem Phys 2001. [DOI: 10.1063/1.1331106] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
The present atmosphere of Titan exhibits evidence of extensive evolution, in the form of rapid photochemical destruction of methane and a large fractionation of the nitrogen and oxygen isotopes. Attempts to recover the initial inventory of volatiles lead toward a model in which nitrogen was originally supplied as NH3, essentially unmodified from its relative abundance in the outer solar nebula. Titan's atmospheric methane, in contrast, appears to have been formed from carbon and other carbon compounds, either by gas phase reactions in the subnebula or by accretional heating during the formation of Titan. These conclusions can be tested by further studies of abundances and isotope ratios in Titan's atmosphere, augmented by studies of comets. The possible similarity of carbon and nitrogen inventories on Titan to those on the inner planets makes this investigation particularly intriguing.
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Affiliation(s)
- T C Owen
- Institute for Astronomy, University of Hawaii, Honolulu 96822, USA.
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Abstract
We consider four-aspects of interstellar chemistry for comparison with comets: molecular abundances in general, relative abundances of isomers (specifically, HCN and HNC), ortho/para ratios for molecules, and isotopic fractionation, particularly for the ratio hydrogen/deuterium. Since the environment in which the solar system formed is not well constrained, we consider both isolated dark clouds where low mass stars may form and the "hot cores" that are the sites of high mass star formation. Attention is concentrated on the gas phase, since the grains are considered elsewhere in this volume.
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Affiliation(s)
- W M Irvine
- Department of Physics and Astronomy, University of Massachusetts, Amherst 01003-4517, USA.
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