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Pla P, Dubosq C, Rapacioli M, Posenitskiy E, Alcamí M, Simon A. Hydrogenation of C 24 Carbon Clusters: Structural Diversity and Energetic Properties. J Phys Chem A 2021; 125:5273-5288. [PMID: 34132096 DOI: 10.1021/acs.jpca.1c02359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This work aims at exploring the potential energy surfaces of C24Hn=0,6,12,18,24 using the genetic algorithm in combination with the density functional based tight binding potential. The structural diversity was analyzed using order parameters, in particular the sum of the numbers of 5- and 6-carbon rings R5/6. The most abundant and lowest energy population was designated as the flake population (isomers of variable shapes, large R5/6 values), characterized by an increasing number of spherical isomers when nH/nC increases. Simultaneously, the fraction of the pretzel population (spherical isomers, smaller R5/6 values) increases. The fraction of the cage population (largest R5/6 values) remains extremely minor while the branched population (smallest R5/6 values) remains the highest energy population for all nH/nC ratios. For all C24Hn=0,6,12,18,24 clusters, the evolution of the carbon ring size distribution with energy clearly shows the correlation between the stability and the number of 6-carbon rings. The average values of the ionization potentials of all populations were found to decrease when nH/nC increases, ranging from 7.9 down to 6.4 eV. This trend was correlated to geometric and electronic factors, in particular to carbon hybridization. These results are of astrophysical interest, especially regarding the role of carbon species in the gas ionization.
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Affiliation(s)
- Paula Pla
- Departamento de Química, Universidad Autónoma de Madrid, Módulo 13, 28049 Madrid, Spain
| | - Clément Dubosq
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université Toulouse UT3 and CNRS, UMR5626, 118 Route Narbonne, F-31062 Toulouse, France
| | - Mathias Rapacioli
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université Toulouse UT3 and CNRS, UMR5626, 118 Route Narbonne, F-31062 Toulouse, France
| | - Evgeny Posenitskiy
- Laboratoire Collisions Agrégats et Réactivité (LCAR), Université de Toulouse (UPS) and CNRS, UMR5589, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Manuel Alcamí
- Departamento de Química, Universidad Autónoma de Madrid, Módulo 13, 28049 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), 28049 Madrid, Spain
- Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Aude Simon
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université Toulouse UT3 and CNRS, UMR5626, 118 Route Narbonne, F-31062 Toulouse, France
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Lykhin AO, Ahmadvand S, Varganov SA. Electronic Transitions Responsible for C 60+ Diffuse Interstellar Bands. J Phys Chem Lett 2019; 10:115-120. [PMID: 30560674 DOI: 10.1021/acs.jpclett.8b03534] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Diffuse interstellar bands (DIBs) are puzzling absorption features believed to contain critical information about molecular evolution in space. Despite the fact that C60+ recently became the first confirmed carrier of several DIBs, the nature of the corresponding transitions is not understood. Using electronic structure methods, we show that the two strong C60+ DIBs cannot be explained by electronic transitions to the two different excited 2 E1 g states or the two spin-orbit components of the lowest 2 E1 g state, as suggested before. We argue that the strong DIBs at 9632 and 9577 Å correspond to the cold excitations from the non-Franck-Condon region of the ground electronic state to the two components of the lowest 2 E1 g state split by Jahn-Teller distortion. The weak DIBs at 9428 and 9365 Å are assigned to the first vibronic transitions involving the low-energy vibrational modes and components of the lowest 2 E1 g electronic state.
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Affiliation(s)
- Aleksandr O Lykhin
- Department of Chemistry , University of Nevada, Reno , 1664 North Virginia Street , Reno , Nevada 89557-0216 , United States
| | - Seyedsaeid Ahmadvand
- Department of Chemistry , University of Nevada, Reno , 1664 North Virginia Street , Reno , Nevada 89557-0216 , United States
| | - Sergey A Varganov
- Department of Chemistry , University of Nevada, Reno , 1664 North Virginia Street , Reno , Nevada 89557-0216 , United States
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Jones AP. Dust evolution, a global view I. Nanoparticles, nascence, nitrogen and natural selection … joining the dots. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160221. [PMID: 28083088 PMCID: PMC5210670 DOI: 10.1098/rsos.160221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 11/14/2016] [Indexed: 05/25/2023]
Abstract
The role and importance of nanoparticles for interstellar chemistry and beyond is explored within the framework of The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS), focusing on their active surface chemistry, the effects of nitrogen doping and the natural selection of interesting nanoparticle sub-structures. Nanoparticle-driven chemistry, and in particular the role of intrinsic epoxide-type structures, could provide a viable route to the observed gas phase OH in tenuous interstellar clouds en route to becoming molecular clouds. The aromatic-rich moieties present in asphaltenes probably provide a viable model for the structures present within aromatic-rich interstellar carbonaceous grains. The observed doping of such nanoparticle structures with nitrogen, if also prevalent in interstellar dust, could perhaps have important and observable consequences for surface chemistry and the formation of precursor pre-biotic species.
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Affiliation(s)
- A. P. Jones
- Institut d’Astrophysique Spatiale, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Bât. 121, 91405 Orsay cedex, France
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Jones AP. Dust evolution, a global view: III. Core/mantle grains, organic nano-globules, comets and surface chemistry. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160224. [PMID: 28083090 PMCID: PMC5210672 DOI: 10.1098/rsos.160224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 11/04/2016] [Indexed: 05/11/2023]
Abstract
Within the framework of The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS), this work explores the surface processes and chemistry relating to core/mantle interstellar and cometary grain structures and their influence on the nature of these fascinating particles. It appears that a realistic consideration of the nature and chemical reactivity of interstellar grain surfaces could self-consistently and within a coherent framework explain: the anomalous oxygen depletion, the nature of the CO dark gas, the formation of 'polar ice' mantles, the red wing on the 3 μm water ice band, the basis for the O-rich chemistry observed in hot cores, the origin of organic nano-globules and the 3.2 μm 'carbonyl' absorption band observed in comet reflectance spectra. It is proposed that the reaction of gas phase species with carbonaceous a-C(:H) grain surfaces in the interstellar medium, in particular the incorporation of atomic oxygen into grain surfaces in epoxide functional groups, is the key to explaining these observations. Thus, the chemistry of cosmic dust is much more intimately related with that of the interstellar gas than has previously been considered. The current models for interstellar gas and dust chemistry will therefore most likely need to be fundamentally modified to include these new grain surface processes.
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Affiliation(s)
- A. P. Jones
- Author for correspondence: A. P. Jones e-mail:
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