First Astronomical Detection of the Cumulene Carbon Chain Molecule H[TINF]2[/TINF]C[TINF]6[/TINF] in TMC-1

Langer, W. D.; Velusamy, T.; Kuiper, T. B. H.; Peng, R.; McCarthy, Michael; Travers, Michael J.; Kovács, A.; Gottlieb, C. A.; Thaddeus, P.

doi:10.1086/310622

Cited by 105 publications

(68 citation statements)

References 14 publications

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“…The onset of the weak system B changes with respect to the origin band of the strong one C passing from HC 9 H + to HC 15 H + . In the case of HC 9 H + it lies on the long-wavelength side of the origin of C , while for HC 13 H + it is blueshifted, for HC 15 H + it is again to the red. The electronic spectrum of HC 11 H + ͑Fig.…”

Section: B Visible Spectral Rangementioning

confidence: 88%

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Higher energy electronic transitions of HC2n+1H+ (n=2–7) and HC2n+1H (n=4–7) in neon matrices

Fulara

Nagy

Garkusha

et al. 2010

The Journal of Chemical Physics

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Electronic absorption spectra of linear HC 2n+1 H + ͑n =2-7͒ were recorded in 6 K neon matrices following their mass-selective deposition. Four new electronic band systems are identified; the strongest Ẽ 2 ⌸ g/u ← X 2 ⌸ u/g lies in the UV and the second most intense C 2 ⌸ g/u ← X 2 ⌸ u/g is located in the visible range. The known Ã 2 ⌸ g/u ← X 2 ⌸ u/g absorption is an order of magnitude weaker than C 2 ⌸ g/u ← X 2 ⌸ u/g . Transitions to the B and D states are also discussed. The wavelengths of the HC 2n+1 H + ͑n =2-7͒ electronic systems obey a linear relation as a function of the size of the cations, similar to other carbon chains. The B 3 ⌺ u − ← X 3 ⌺ g − transition in the UV of neutral HC 2n+1 H ͑n =4-7͒ has also been identified upon photobleaching of the cations trapped in the matrices.

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Section: B Visible Spectral Rangementioning

confidence: 88%

“…HC 2n+1 H ͑n =3-6,9͒ have been studied in the gas-phase by means of a resonant two-color two-photon ionization technique. 19 The wavelength of the origin band of HC 13 H in the gas-phase is found at 281.82 nm and at 290.0 nm in a neon matrix. Smaller members of HC 2n+1 H ͑n =2-4͒ have been studied by ab initio CASSCF and MRD-CI methods.…”

Section: -5mentioning

confidence: 99%

Higher energy electronic transitions of HC2n+1H+ (n=2–7) and HC2n+1H (n=4–7) in neon matrices

Fulara

Nagy

Garkusha

et al. 2010

The Journal of Chemical Physics

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“…As we use the UMIST 95 ratefile, we perform a similar analysis for this database. The observed abundances for TMC-1 and L134N are taken from Ohishi et al (1992) and Langer et al (1997). Following Terzieva & Herbst (1998b), we assume that the abundance of a given molecule is consistent with observational data if it lies within an order of magnitude of the observed abundance.…”

Section: Initial Conditions For Chemistrymentioning

confidence: 99%

Reduction of chemical networks

Semenov¹,

Wiebe²,

Henning³

2004

A&A

143

170

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Abstract.We analyse the evolution of the fractional ionisation in a steady-state protoplanetary disc over 10 6 yr. We consider a disc model with a vertical temperature gradient and with gas-grain chemistry including surface reactions. The ionisation due to stellar X-rays, stellar and interstellar UV radiation, cosmic rays and radionuclide decay is taken into account. Using our reduction schemes as a tool for the analysis, we isolate small sets of chemical reactions that reproduce the evolution of the ionisation degree at representative disc locations with an accuracy of 50%-100%. On the basis of fractional ionisation, the disc can be divided into three distinct layers. In the dark dense midplane the ionisation degree is sustained by cosmic rays and radionuclides only and is very low, < ∼ 10 −12 . This region corresponds to the so-called "dead zone" in terms of the angular momentum transport driven by MHD turbulence. The ionisation degree can be accurately reproduced by chemical networks with about 10 species and a similar number of reactions. In the intermediate layer the chemistry of the fractional ionisation is driven mainly by the attenuated stellar X-rays and is far more complicated. For the first time, we argue that surface hydrogenation of long carbon chains can be of crucial importance for the evolution of the ionisation degree in protoplanetary discs. In the intermediate layer reduced networks contain more than a 100 species and hundreds of reactions. Finally, in the unshielded low-density surface layer of the disc the chemical life cycle of the ionisation degree comprises a restricted set of photoionisation-recombination processes. It is sufficient to keep about 20 species and reactions in reduced networks. Furthermore, column densities of key molecules are calculated and compared to the results of other recent studies and observational data. The relevance of our results to the MHD modelling of protoplanetary discs is discussed.

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“…But the existence of such substituted cumulene-containing aromatic molecules is quite plausible both from the chemical point of view (Norman et al 1999), and particularly from the astrophysical one, since they are suggested by the analysis of infrared spectra (Duley 2000) and free cumulene chains have been widely detected in molecular clouds (Cernicharo et al 1991;Langer et al 1997). Moreover it has been recently established that chains like C 2 H or C 4 H are also abundant in photodissociation regions, despite the strong UV field.…”

Section: Photoinduced Productsmentioning

confidence: 99%

Photoinduced products from cold coronene clusters

Bréchignac¹,

Schmidt

Masson

et al. 2005

A&A

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Free cold pure coronene clusters have been formed in a gas aggregation source and irradiated with excimer laser pulses. Analysis of the photoproducts thanks to a reflectron time-of-flight mass spectrometer showed that new ionic compounds are formed. These species may include Polycyclic Aromatic Hydrocarbons (PAHs) larger than coronene, PAH-coronene clusters, as well as coronene clusters branched with unsaturated aliphatic chains. The relevance of these results in the context of interstellar medium chemistry, and in particular the carriers of the so-called aromatic infrared emission bands (AIBs), is discussed.

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First Astronomical Detection of the Cumulene Carbon Chain Molecule H[TINF]2[/TINF]C[TINF]6[/TINF] in TMC-1

Cited by 105 publications

References 14 publications

Higher energy electronic transitions of HC2n+1H+ (n=2–7) and HC2n+1H (n=4–7) in neon matrices

Higher energy electronic transitions of HC2n+1H+ (n=2–7) and HC2n+1H (n=4–7) in neon matrices

Reduction of chemical networks

Photoinduced products from cold coronene clusters

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