Low-temperature nitrogen-bearing polycyclic aromatic hydrocarbon formation routes validated by infrared spectroscopy

Rap, Daniël B.; Schrauwen, Johanna G.M.; Marimuthu, Aravindh N.; Redlich, Britta; Brünken, Sandra

doi:10.1038/s41550-022-01713-z

Cited by 18 publications

(32 citation statements)

References 61 publications

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“…Notably, the same model generally reproduces the observed abundances of linear and mono-cyclic nitriles 3 , but underpredicts the abundance of bicyclic indene by four orders of magnitude 4 . Laboratory studies have shown that nitrogen bearing aromatic molecules 5 , as well as pure hydrocarbons like naphthalene 6 and indene 4 , 7 , may be readily formed in barrierless, gas-phase ion-molecule and radical-molecule reactions under conditions similar to those in interstellar clouds. On the other hand, the model of McGuire et al indicates rapid depletion of CNN from TMC-1 through interactions with ions, 3 and it predicts a limited abundance of its main precursor, naphthalene, which has also been shown to be a keystone in the formation of larger PAHs 8 .…”

Section: Introductionmentioning

confidence: 99%

Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds

et al. 2023

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After decades of searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C10H7CN) in the Taurus Molecular Cloud (TMC-1) is six orders of magnitude higher than expected from astrophysical modeling. Here, we report unimolecular dissociation and radiative cooling rate coefficients of the 1-CNN isomer in its cationic form. These results are based on measurements of the time-dependent neutral product emission rate and kinetic energy release distributions produced from an ensemble of internally excited 1-CNN+ studied in an environment similar to that in interstellar clouds. We find that Recurrent Fluorescence – radiative relaxation via thermally populated electronic excited states – efficiently stabilizes 1-CNN+, owing to a large enhancement of the electronic transition probability by vibronic coupling. Our results help explain the anomalous abundance of CNN in TMC-1 and challenge the widely accepted picture of rapid destruction of small PAHs in space.

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Section: Introductionmentioning

confidence: 99%

Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds

et al. 2023

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“…Very recently, ion−molecule reactions are considered to play an important role in the growth of nitrogen- bearing PAHs in space. 44 This study also would broaden our knowledge of the evolution of complex organic molecules through ion−molecule reactions in space.…”

Section: T H Imentioning

confidence: 93%

“…These gaseous ion–molecule reactions may also occur in extraterrestrial space with the related interstellar molecules ionized by cosmic rays or internal ultraviolet photons. Very recently, ion–molecule reactions are considered to play an important role in the growth of nitrogen-bearing PAHs in space . This study also would broaden our knowledge of the evolution of complex organic molecules through ion–molecule reactions in space.…”

mentioning

confidence: 87%

A Facile Route for the Formation of Complex Nitrogen-Containing Prebiotic Molecules in the Interstellar Medium

Xie

Sun

et al. 2022

J. Phys. Chem. Lett.

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Prebiotic molecules have often been identified in the interstellar medium and meteorite samples. However, we still have only a fragmentary knowledge of the mechanism of the evolutionary process of these prebiotic molecules. With the aid of state-of-the-art vacuum ultraviolet (VUV)-infrared (IR) spectroscopy and ab initio calculations, we reveal a new pathway leading to the formation of the biorelevant molecules carrying amine groups or peptide bonds via the single-photon ionization induced Michael/cyclization reaction of acrylonitrile (AN)−alcohol heterodimer complexes in the gas phase. In the reactions, not only N−H nitrilium cations with H + −N�C−R Lewis structure but also cyclic amine cations with a peptide bond can be formed when the AN reacts with alcohols of increasing molecular size (such as ethanol, propanol, or butanol). This study suggests the possibility of unsaturated nitriles being reduced by ionized alcohols in space, which can further drive sequential Michael addition/cyclization reactions to form more complex biorelevant molecules.

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“…Following the chemical rules for aromaticity, the PAH interstellar formation mechanisms, nitrogen, which is isoelectronic with CH, can be substituted for carbon atoms, forming polycyclic aromatic nitrogen heterocycles (PANHs). Nitrogen insertion may be an important phenomenon in the PAH life cycle that affects the emission profiles and positions significantly . PANHs can help in explaining the 6.2 μm (6200 nm) profile as well as other features very well. , The constraints of cosmic abundance stipulate that the interstellar PAH population could include PANHs in a significant amount. , The detection of PANHs in carbonaceous meteorites and in the form of PAH nitriles , in TMC-1, a molecular cloud, suggests their significant presence in the ISM.…”

Section: Introductionmentioning

confidence: 99%

“…Nitrogen insertion may be an important phenomenon in the PAH life cycle that affects the emission profiles and positions significantly. 45 PANHs can help in explaining the 6.2 μm (6200 nm) profile as well as other features very well. 46,47 The constraints of cosmic abundance stipulate that the interstellar PAH population could include PANHs in a significant amount.…”

Section: ■ Introductionmentioning

confidence: 99%

Time-Dependent Density Functional Study of Nitrogen-Substituted Polycyclic Aromatic Hydrocarbons and Diffuse Interstellar Bands

Shukla

Vats

Pathak

et al. 2022

ACS Earth Space Chem.

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This work reports theoretical calculations of electronic transitions in nitrogen-substituted polycyclic aromatic hydrocarbon neutrals and cations, using time-dependent density functional theory. The results obtained are compared with the diffuse interstellar bands, a broad group of absorption bands that can be seen mostly in near-ultraviolet and near-infrared wavelengths of the spectrum. It is observed that with nitrogen substituted at the periphery (exoskeletal), these nitrogen-substituted polycyclic aromatic hydrocarbon neutrals and their cation counterparts, similar to their corresponding parent polycyclic aromatic hydrocarbons, absorb in the near-ultraviolet and near-infrared wavelengths, respectively. The analogy then follows a change with nitrogen entering into the structure (endoskeletal) and the nitrogen-substituted polycyclic aromatic hydrocarbon neutrals and cations, unlike their corresponding pure polycyclic aromatic hydrocarbon family, fall in the near-infrared and visible spectral regions, respectively. Based on these and other astrophysical implications, it is concluded that nitrogen-substituted polycyclic aromatic hydrocarbons represent a powerful class of prospective carriers of diffuse interstellar bands.

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Low-temperature nitrogen-bearing polycyclic aromatic hydrocarbon formation routes validated by infrared spectroscopy

Cited by 18 publications

References 61 publications

Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds

Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds

A Facile Route for the Formation of Complex Nitrogen-Containing Prebiotic Molecules in the Interstellar Medium

Time-Dependent Density Functional Study of Nitrogen-Substituted Polycyclic Aromatic Hydrocarbons and Diffuse Interstellar Bands

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