Enhanced reactivity of oxygen-functionalised PAHs with atomic hydrogen – A route to the formation of small oxygen-carrying molecules

Jaganathan, Rijutha; Simonsen, Frederik Doktor S.; Thrower, J. D.; Hornekær, Liv

doi:10.1051/0004-6361/202243312

Cited by 7 publications

(3 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both protonated PQ and PHQ show a similar fragmentation behavior with two main dissociation channels, located for PQ at (283 ± 2) and (257 ± 2) amu, and for PHQ at (186 ± 2) and (156 ± 2) amu, which is in excellent agreement with previously measured electron impact ionization mass spectra (NIST Mass Spectrometry Data Center, William E. Wallace, Director 2023; Jaganathan et al 2022). We measured two additional, less intense, dissociation channels for PQ at (156±2) and (128±2) amu (see insert in Fig.…”

Section: Daughter-mass Spectrometrysupporting

confidence: 88%

Gas-phase electronic action absorption spectra of protonated oxygen-functionalized polycyclic aromatic hydrocarbons (OPAHs)

Rasmussen¹,

Wenzel²,

Hornekær³

et al. 2023

A&A

View full text Add to dashboard Cite

Context. Extended red emission (ERE) denotes a broad unassigned feature extending from 540 to 800 nm observed in many regions of the interstellar medium (ISM), and is thought to originate from photoluminescence of cosmic dust. However, definitive assignment of specific carriers remains to be achieved. Aims. Our aim is to investigate the photoabsorption spectra of astrophysically relevant protonated oxygen-functionalized polycyclic aromatic hydrocarbons (OPAHs) to probe their ability to absorb photons in the near-ultraviolet (UV) and visible (vis) spectral region and to search for any low-lying electronic states that may account for the ERE. Methods. Gas-phase electronic action absorption spectra of the protonated OPAHs were recorded in the spectral range of 200−700 nm using the ELISA ion-storage ring. Additional time-dependent density functional theory (TD-DFT) calculations were performed to compute excited state transitions that complement the experimental spectra. Results. A set of five protonated (O)PAHs was considered, namely pentacene and the four oxygen-functionalized PAHs, pentacenequinone, pentacenetetrone, anthraquinone, and phenathrenequinone. All pentacene-related species show a main absorption band between 400 and 500 nm, while the smaller OPAHs, anthraquinone and phenanthrenequinone, generally absorb further to the blue compared to the pentacenes. Interestingly, pentacenequinone and phenanthrenequinone exhibit wide absorption plateaus towards the red side of their main absorption band(s), which places them among the potential candidates to contribute to ERE. Additional photodissociation mass spectra reveal the formation of smaller functionalized PAHs and small oxygen-bearing species. Conclusions. Our results demonstrate the ability of OPAHs to absorb in the UV/vis spectral region. Among the four studied OPAHs, two revealed very broad absorption characteristics at wavelengths up to 700 nm, which makes them suitable candidates to contribute to a part of the ERE spectrum. Moreover, these two OPAHs, pentacenequinone and phenanthrenequinone, could dissociate efficiently into oxygen-bearing molecules and smaller functionalized PAHs in photon-dominated regions (PDRs) of the ISM.

show abstract

Section: Daughter-mass Spectrometrysupporting

confidence: 88%

Gas-phase electronic action absorption spectra of protonated oxygen-functionalized polycyclic aromatic hydrocarbons (OPAHs)

Rasmussen¹,

Wenzel²,

Hornekær³

et al. 2023

A&A

View full text Add to dashboard Cite

show abstract

“…The active development of carbocatalysis in the last decade has shown that important catalytic processes can proceed even without the participation of metals. Several decades ago, PAHs were noted to be appropriate for H 2 formation in PDRs. , Functionalized PAHs with oxygen-bearing groups can be a source of small oxygen-bearing molecules under conditions of UV irradiation in the ISM. , Recently, it has been shown that PAHs can also be catalysts for many other hydrogenation reactions in the ISM, resulting in the synthesis of molecules such as H 2 O and HCO . Similarly, under certain conditions, PAHs can play a role in the synthesis of benzene from simple precursors.…”

Section: Catalytic Reactions In Space With Acetylenementioning

confidence: 99%

“…463,464 Functionalized PAHs with oxygen-bearing groups can be a source of small oxygen-bearing molecules under conditions of UV irradiation in the ISM. 465,466 Recently, it has been shown that PAHs can also be catalysts for many other hydrogenation reactions in the ISM, resulting in the synthesis of molecules such as H 2 O and HCO. 467 Similarly, under certain conditions, PAHs can play a role in the synthesis of benzene from simple precursors.…”

Section: Catalytic Reactions Involving Acetylene In Spacementioning

confidence: 99%

Role of Acetylene in the Chemical Evolution of Carbon Complexity

Pentsak,

Murga,

Ananikov

2024

ACS Earth Space Chem.

View full text Add to dashboard Cite

Acetylene, among the multitude of organic molecules discovered in space, plays a distinct role in the genesis of organic matter. Characterized by its unique balance of stability and reactivity, acetylene is the simplest unsaturated organic molecule known to have a triple bond. In addition to its inherent chemical properties, acetylene is one of the most prevalent organic molecules found across the Universe, spanning from the icy surfaces of planets and satellites and the cold interstellar medium with low temperatures to hot circumstellar envelopes where temperatures surge to several thousand kelvins. These factors collectively position acetylene as a crucial building block in the molecular diversification of organic molecules and solids present in space. This review comprehensively discusses the formation and expansion of carbon skeletons involving acetylene, ranging from the formation of simple molecules to the origination of the first aromatic ring and ultimately to the formation of nanosized carbon particles. Mechanisms pertinent to both hot environments, such as circumstellar envelopes, and cold environments, including molecular clouds and planetary atmospheres, are explored. In addition, this review contemplates the role of acetylene in the synthesis of prebiotic molecules. A distinct focus is accorded to the recent advancements and future prospects of research into catalytic processes involving acetylene molecules, which is a significant instrument in driving the evolution of carbon complexity in the Universe. The insights garnered from this review underscore the significance of acetylene in astrochemistry and potentially contribute to our understanding of the chemical evolution of the Universe.

show abstract