Infrared spectra of complex organic molecules in astronomically relevant ice matrices. III. Methyl formate and its tentative solid-state detection

AbstractExperimental and theoretical studies have shown that Complex Organic Molecules (COMs) can be formed on icy dusty grains in molecular clouds and protoplanetary disks. The number of astronomical detections of solid COMs, however, is very limited. With the upcoming launch of the James Webb Space Telescope (JWST) this should change, but in order to identify solid state features of COMs, accurate laboratory data are needed. Here we present high resolution (0.5 cm–1) infrared ice spectra of acetone (C3H6O) and methyl formate (HCOOCH3), two molecules already identified in astronomical gas phase surveys, whose interstellar synthesis is expected to follow solid state pathways.

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Infrared spectra of complex organic molecules in astronomically relevant ice matrices

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319008780 ◽

2019 ◽

Vol 15 (S350) ◽

pp. 356-357

Author(s):

J. Terwisscha van Scheltinga ◽

N. F. W. Ligterink ◽

A. C. A. Boogert ◽

E. F. van Dishoeck ◽

H. Linnartz

Keyword(s):

Solid State ◽

Gas Phase ◽

Infrared Spectra ◽

Organic Molecules ◽

Laboratory Studies ◽

Astronomical Observations ◽

James Webb Space Telescope ◽

Circumstellar Gas ◽

Complex Organic ◽

Recent Laboratory

AbstractThe identification of complex organic molecules, COMs, in inter- and circumstellar gas phase environments is steadily increasing. The formation of such COMs takes largely place on the icy dust grains, as has been shown in recent laboratory studies. Until now solid state features of smaller molecular species have been directly identified in these environments. The presented work on acetaldehyde (CH3CHO), ethanol (CH3CH2OH), and dimethyl ether (CH3OCH3) in different astronomically relevant ice environments and for temperatures in the range 15 to 160 Kelvin, provides the necessary tools to guide or interpret astronomical observations, specifically for upcoming James Webb Space Telescope observations.

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Far-infrared spectra of some complex organic molecules at liquid helium temperature∗

Infrared Physics ◽

10.1016/0020-0891(76)90074-9 ◽

1976 ◽

Vol 16 (5) ◽

pp. 535-542 ◽

Cited By ~ 4

Author(s):

M. Hineno ◽

H. Yoshinaga

Keyword(s):

Liquid Helium ◽

Infrared Spectra ◽

Organic Molecules ◽

Far Infrared ◽

Liquid Helium Temperature ◽

Helium Temperature ◽

Complex Organic ◽

Far Infrared Spectra

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Infrared spectra of complex organic molecules in astronomically relevant ice mixtures. IV. Methylamine

Astronomy and Astrophysics ◽

10.1051/0004-6361/202140782 ◽

2021 ◽

Author(s):

M. G. Rachid ◽

N. Brunken ◽

D de Boe ◽

G. Fedoseev ◽

A. C. A. Boogert ◽

...

Keyword(s):

Infrared Spectra ◽

Organic Molecules ◽

Complex Organic

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Dust and molecules in extra-galactic planetary nebulae

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317000357 ◽

2015 ◽

Vol 11 (A29B) ◽

Author(s):

D. A. García-Hernández

Keyword(s):

Solid State ◽

Gas Phase ◽

Organic Molecules ◽

Local Group ◽

Planetary Nebulae ◽

Circumstellar Envelopes ◽

The Galaxy ◽

Models Comparison ◽

Polycyclic Aromatic ◽

Complex Organic

AbstractExtra-galactic planetary nebulae (PNe) permit the study of dust and molecules in metallicity environments other than the Galaxy. Their known distances lower the number of free parameters in the observations vs. models comparison, providing strong constraints on the gas-phase and solid-state astrochemistry models. Observations of PNe in the Galaxy and other Local Group galaxies such as the Magellanic Clouds (MC) provide evidence that metallicity affects the production of dust as well as the formation of complex organic molecules and inorganic solid-state compounds in their circumstellar envelopes. In particular, the lower metallicity MC environments seem to be less favorable to dust production and the frequency of carbonaceous dust features and complex fullerene molecules is generally higher with decreasing metallicity. Here, I present an observational review of the dust and molecular content in extra-galactic PNe as compared to their higher metallicity Galactic counterparts. A special attention is given to the level of dust processing and the formation of complex organic molecules (e.g., polycyclic aromatic hydrocarbons, fullerenes, and graphene precursors) depending on metallicity.

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Infrared spectra of complex organic molecules in astronomically relevant ice mixtures

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037497 ◽

2020 ◽

Vol 639 ◽

pp. A4

Author(s):

M. G. Rachid ◽

J. Terwisscha van Scheltinga ◽

D. Koletzki ◽

H. Linnartz

Keyword(s):

Ir Spectra ◽

Infrared Spectra ◽

Organic Molecules ◽

Solid Phase ◽

High Vacuum ◽

Peak Position ◽

Large Set ◽

Complex Species ◽

Asymmetric Stretch ◽

Complex Organic

Context. Complex organic molecules (COMs) have been largely identified through their characteristic rotational transitions in the gas of interstellar and circumstellar regions. Although these species are formed in the icy mantles that cover dust grains, the most complex species that has been unambiguously identified in the solid-phase to date is methanol (CH3OH). With the upcoming launch of the James Webb Space Telescope (JWST), this situation may change. The higher sensitivity, spectral and spatial resolution of the JWST will allow for the probing of the chemical inventory of ices in star-forming regions. In order to identify features of solid-state molecules in astronomical spectra, laboratory infrared spectra of COMs within astronomically relevant conditions are required. This paper is part of a series of laboratory studies focusing on the infrared spectra of frozen COMs embedded in ice matrices. These reflect the environmental conditions in which COMs are thought to be found. Aims. This work is aimed at characterizing the infrared features of acetone mixed in ice matrices containing H2O, CO2, CO, CH4, and CH3OH for temperatures ranging between 15 K and 160 K. Changes in the band positions and shapes due to variations in the temperature, ice composition, and morphology are reported. This work also points out the IR features that are considered the best promising tracers when searching for interstellar acetone-containing ices. Methods. Acetone-containing ices were grown at 15 K under high-vacuum conditions and infrared (IR) spectra (500–4000 cm−1/20–2.5 μm, 0.5 cm−1 resolution) in transmission mode were recorded using a Fourier transform infrared spectrometer. Spectra of the ices at higher temperatures are acquired during the heating of the sample (at a rate of 25 K h−1) up to 160 K. The changes in the infrared features for varying conditions were analyzed. Results. A large set of IR spectra of acetone-containing ices is presented and made available as a basis for interpreting current and future infrared astronomical spectra. The peak position and full width at half maximum of selected acetone bands have been measured for different ice mixtures and temperatures. The bands that are best suitable for acetone identification in astronomical spectra are: the C=O stretch mode, around 1710.3 cm−1 (5.847 μm), that lies in the 1715–1695 cm−1 (5.83–5.90 μm) range in the mixed ices; the CH3 symmetric deformation, around 1363.4 cm−1 (7.335 μm) that lies in the 1353–1373 cm−1 (7.28–7.39 μm) range in the mixed ices; and the CCC asymmetric stretch, around 1228.4 cm−1 (8.141 μm), that lies in the 1224–1245 cm−1 (8.16–8.03 μm) range in the mixed ices. The CCC asymmetric stretch band also exhibits potential as a remote probe of the ice temperature and composition; this feature is the superposition of two components that respond differently to temperature and the presence of CH3OH. All the spectra are available through the Leiden Ice Database.

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Molecular processes from the AGB to the PN stage

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312010861 ◽

2011 ◽

Vol 7 (S283) ◽

pp. 148-155 ◽

Cited By ~ 1

Author(s):

D. Anibal García-Hernández

Keyword(s):

Solid State ◽

Stellar Evolution ◽

Organic Molecules ◽

Asymptotic Giant Branch ◽

Molecular Processes ◽

Polycyclic Aromatic ◽

Circumstellar Shell ◽

Pn Stage ◽

Complex Organic ◽

Late Stages

AbstractMany complex organic molecules and inorganic solid-state compounds have been observed in the circumstellar shell of stars (both C-rich and O-rich) in the transition phase between Asymptotic Giant Branch (AGB) stars and Planetary Nebulae (PNe). This short (~102-104 years) phase of stellar evolution represents a wonderful laboratory for astrochemistry and provides severe constraints on any model of gas-phase and solid-state chemistry. One of the major challenges of present day astrophysics and astrochemistry is to understand the formation pathways of these complex organic molecules and inorganic solid-state compounds (e.g., polycyclic aromatic hydrocarbons, fullerenes, and graphene in the case of a C-rich chemistry and oxides and crystalline silicates in O-rich environments) in space. In this review, I present an observational review of the molecular processes in the late stages of stellar evolution with a special emphasis on the first detections of fullerenes and graphene in PNe.

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The ALMA-PILS survey: the first detection of doubly deuterated methyl formate (CHD2OCHO) in the ISM

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832844 ◽

2019 ◽

Vol 623 ◽

pp. A69 ◽

Cited By ~ 16

Author(s):

S. Manigand ◽

H. Calcutt ◽

J. K. Jørgensen ◽

V. Taquet ◽

H. S. P. Müller ◽

...

Keyword(s):

Star Formation ◽

Organic Molecules ◽

Methyl Formate ◽

Local Thermal Equilibrium ◽

Organic Species ◽

Physical Conditions ◽

Methyl Cyanide ◽

Model Tracing ◽

Star Formation Regions ◽

Complex Organic

Studies of deuterated isotopologues of complex organic molecules can provide important constraints on their origin in star formation regions. In particular, the abundances of deuterated species are very sensitive to the physical conditions in the environment where they form. Because the temperatures in star formation regions are low, these isotopologues are enhanced to significant levels, which enables the detection of multiply deuterated species. However, for complex organic species, so far only the multiply deuterated variants of methanol and methyl cyanide have been reported. The aim of this paper is to initiate the characterisation of multiply deuterated variants of complex organic species with the first detection of doubly deuterated methyl formate, CHD2OCHO. We use ALMA observations from the Protostellar Interferometric Line Survey (PILS) of the protostellar binary IRAS 16293–2422 in the spectral range of 329.1 GHz to 362.9 GHz. Spectra towards each of the two protostars are extracted and analysed using a local thermal equilibrium model in order to derive the abundances of methyl formate and its deuterated variants. We report the first detection of doubly deuterated methyl formate CHD2OCHO in the ISM. The D-to-H ratio (D/H ratio) of CHD2OCHO is found to be 2–3 times higher than the D/H ratio of CH2DOCHO for both sources, similar to the results for formaldehyde from the same dataset. The observations are compared to a gas-grain chemical network coupled to a dynamical physical model, tracing the evolution of a molecular cloud until the end of the Class 0 protostellar stage. The overall D/H ratio enhancements found in the observations are of about the same magnitude as the predictions from the model for the early stages of Class 0 protostars. However, that the D/H ratio of CHD2OCHO is higher than that of CH2DOCHO is still not predicted by the model. This suggests that a mechanism enhances the D/H ratio of singly and doubly deuterated methyl formate that is not in the model, for instance, mechanisms for H–D substitutions. This new detection provides an important constraint on the formation routes of methyl formate and outlines a path forward in terms of using these ratios to determine the formation of organic molecules through observations of differently deuterated isotopologues towards embedded protostars.

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Solid-state formation of CO and H2CO via the CHOCHO + H reaction

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3051 ◽

2019 ◽

Vol 491 (1) ◽

pp. 289-301 ◽

Cited By ~ 1

Author(s):

Killian Leroux ◽

Jean-Claude Guillemin ◽

Lahouari Krim

Keyword(s):

Solid State ◽

Ethylene Glycol ◽

Organic Molecules ◽

Solid Phase ◽

Secondary Product ◽

Experimental Conditions ◽

Work Surface ◽

Reaction Intermediate ◽

Complex Organic ◽

Potential Precursor

ABSTRACT Glycolaldehyde (CHOCH2OH) and ethylene glycol (HOCH2CH2OH) are among many complex organic molecules detected in the interstellar medium (ISM). Astrophysical models proposed very often that the formation of these compounds would be directly linked to the hydrogenation of glyoxal (CHOCHO), a potential precursor which is not yet detected in the ISM. We have performed, in this work, surface and bulk hydrogenations of solid CHOCHO under ISM conditions in order to confirm or invalidate the astrophysical modelling of glyoxal transformation. Our results show that the hydrogenation of glyoxal does not lead to the formation of detectable amounts of heavier organic molecules such as glycolaldehyde and ethylene glycol but rather to lighter CO-bearing species such as CO, H2CO, and CO–H2CO, a reaction intermediate resulting from an H-addition–elimination process on CHOCHO and where CO is linked to H2CO. The solid phase formation of such a reaction intermediate has been confirmed through the neon matrix isolation of CO–H2CO species. Additionally, the CHOCHO + H solid-state reaction might also lead to the production of CH3OH formed under our experimental conditions as a secondary product resulting from the hydrogenation of formaldehyde.

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