Production of complex organic molecules:H-atom addition versus UV irradiation

Chuang, K.-J.; Fedoseev, G.; Qasim, Danna; Ioppolo, Sergio; Dishoeck, E. F. van; Linnartz, H.

doi:10.1093/mnras/stx222

Cited by 58 publications

(53 citation statements)

References 88 publications

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“…We also assumed a depletion of F and Cl by a factor 100 with respect to the solar value. We find that the abundance of methyl formate (with respect to H 2 ) in the high temperature regime (100-300 K) varies between ∼7 × 10 −10 and ∼2.5 × 10 −8 once the temperature is above 100 K. Rivilla et al (2017) Even if our simulations predict abundances of methyl formate relatively similar to the observations with just the inclusion of the gas phase mechanism, it was also shown that methyl formate could also form on the grains with ethylene glycol and glycolaldehyde through hydrogenation of CO:H 2 CO:CH 3 OH ice mixtures under certain conditions (Chuang et al 2016;Chuang et al 2017). Running the previous cases after the inclusion of this grain surface mechanism is beyond the scope of this paper.…”

Section: Inclusion Of Methyl Formate Grain Surface Formation Pathwaysupporting

confidence: 60%

Chemical modelling of glycolaldehyde and ethylene glycol in star-forming regions

Coutens

Viti

Rawlings

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Glycolaldehyde (HOCH 2 CHO) and ethylene glycol ((CH 2 OH) 2 ) are two complex organic molecules detected in the hot cores and hot corinos of several star-forming regions. The ethylene glycol/glycolaldehyde abundance ratio seems to show an increase with the source luminosity. In the literature, several surface-chemistry formation mechanisms have been proposed for these two species. With the UCLCHEM chemical code, we explored the different scenarios and compared the predictions for a range of sources of different luminosities with the observations. None of the scenarios reproduce perfectly the trend. A better agreement is, however, found for a formation through recombination of two HCO radicals followed by successive hydrogenations. The reaction between HCO and CH 2 OH could also contribute to the formation of glycolaldehyde in addition to the hydrogenation pathway. The predictions are improved when a trend of decreasing H 2 density within the core region with T≥100 K as a function of luminosity, is included in the model. Destruction reactions of complex organic molecules in the gas phase would also need to be investigated, since they can affect the abundance ratios once the species have desorbed in the warm inner regions of the star-forming regions.

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Section: Inclusion Of Methyl Formate Grain Surface Formation Pathwaysupporting

confidence: 60%

Chemical modelling of glycolaldehyde and ethylene glycol in star-forming regions

Coutens

Viti

Rawlings

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…It is generally accepted that chemical processes in the bulk and on the surface of interstellar ices are essential in facilitating the formation of both rather simple species such as H 2 O 4,5 and CH 3 OH 6 and more complex species, including small sugars and alcohol sugars like glycolaldehyde and glycerol. [7][8][9][10][11][12][13] Laboratory experiments, indeed, confirmed that a) Electronic mail: kofman@strw.leidenuniv.nl molecular complexity in an ice environment can be enhanced through (radiation-induced) radical recombinations, 14,15 atom addition and abstraction reactions, 13,16,17 or upon thermally induced processes during warm-up. [18][19][20][21] Alternatively, larger species such as polycyclic aromatic hydrocarbons (PAHs), typically formed in the ejecta of dying stars, may also directly freeze out onto icy grains.…”

Section: Introductionmentioning

confidence: 75%

A multifunctional setup to record FTIR and UV-vis spectra of organic molecules and their photoproducts in astronomical ices

Kofman

Witlox

Bouwman

et al. 2018

Review of Scientific Instruments

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This article describes a new, multi-functional, high-vacuum ice setup that allows to record the in situ and real-time spectra of vacuum UV (VUV)-irradiated non-volatile molecules embedded in a low-temperature (10 K) amorphous solid water environment. Three complementary diagnostic tools-UV-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopy and temperature-programmed desorption quadrupole mass spectrometry-can be used to simultaneously study the physical and chemical behavior of the organic molecules in the ice upon VUV irradiation. The setup is equipped with a temperature-controlled sublimation oven that enables the controlled homogeneous deposition of solid species such as amino acids, nucleobases, and polycyclic aromatic hydrocarbons (PAHs) in ice mixtures prepared from precursor gases and/or liquids. The resulting ice is photo-processed with a microwave discharge hydrogen lamp, generating VUV radiation with a spectral energy distribution representative for the interstellar medium. The characteristics, performance, and future potential of the system are discussed by describing three different applications. First, a new method is introduced, which uses broadband interference transmission fringes recorded during ice deposition, to determine the wavelength-dependent refractive index, n, of amorphous solid water. This approach is also applicable to other solids, pure and mixed. Second, the UV-vis and FTIR spectroscopy of an VUV-irradiated triphenylene:water ice mixture is discussed, monitoring the ionization efficiency of PAHs in interstellar ice environments. The third and final example investigates the stability of solid glycine upon VUV irradiation by monitoring the formation of dissociation products in real time.

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“…Numerous efforts have been done in the last years to understand how COMs are formed in the insterstellar medium (ISM), by combining observations (e.g., Belloche et al 2009;Jørgensen et al 2016;Martín-Doménech et al 2017;Codella et al 2017;Rivilla et al 2017a,b), chemical modeling (e.g., Garrod et al 2008;Vasyunin & Herbst 2013a,b;Balucani et al 2015;Taquet et al 2016;Vasyunin et al 2017;Coutens et al 2018;Bergantini et al 2018;Quénard et al 2018a), and laboratory experiments (e.g. Fedoseev et al 2015;Chuang et al 2016Chuang et al , 2017. However, despite all efforts, our understanding about the synthesis of COMs in the ISM is still very limited.…”

Section: Introductionmentioning

confidence: 99%

First ALMA maps of HCO, an important precursor of complex organic molecules, towards IRAS 16293–2422

Rivilla

Beltrán

Vasyunin

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The formyl radical HCO has been proposed as the basic precursor of many complex organic molecules such as methanol (CH 3 OH) or glycolaldehyde (CH 2 OHCHO). Using ALMA, we have mapped, for the first time at high angular resolution (∼1 ′′ , ∼140 au), HCO towards the Solar-type protostellar binary IRAS 16293−2422, where numerous complex organic molecules have been previously detected. We also detected several lines of the chemically related species H 2 CO, CH 3 OH and CH 2 OHCHO. The observations revealed compact HCO emission arising from the two protostars. The line profiles also show redshifted absorption produced by foreground material of the circumbinary envelope that is infalling towards the protostars. Additionally, IRAM 30m single-dish data revealed a more extended HCO component arising from the common circumbinary envelope. The comparison between the observed molecular abundances and our chemical model suggests that whereas the extended HCO from the envelope can be formed via gas-phase reactions during the cold collapse of the natal core, the HCO in the hot corinos surrounding the protostars is predominantly formed by the hydrogenation of CO on the surface of dust grains and subsequent thermal desorption during the protostellar phase. The derived abundance of HCO in the dust grains is high enough to produce efficiently more complex species such as H 2 CO, CH 3 OH, and CH 2 OHCHO by surface chemistry. We found that the main formation route of CH 2 OHCHO is the reaction between HCO and CH 2 OH.

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Production of complex organic molecules:H-atom addition versus UV irradiation

Cited by 58 publications

References 88 publications

Chemical modelling of glycolaldehyde and ethylene glycol in star-forming regions

Chemical modelling of glycolaldehyde and ethylene glycol in star-forming regions

A multifunctional setup to record FTIR and UV-vis spectra of organic molecules and their photoproducts in astronomical ices

First ALMA maps of HCO, an important precursor of complex organic molecules, towards IRAS 16293–2422

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