Infrared spectroscopy of solid CO-CO2 mixtures and layers

Abstract

The spectra of pure, mixed and layered CO and CO2 ices have been studied systematically under laboratory conditions using infrared spectroscopy. This work provides improved resolution spectra (0.5 cm-1) of the CO2 bending and asymmetric stretching mode, as well as the CO stretching mode, extending the existing Leiden database of laboratory spectra to match the spectral resolution reached by modern telescopes and to support the interpretation of the most recent data from Spitzer. It is shown that mixed and layered CO and CO2 ices exhibit very different spectral characteristics, which depend critically on thermal annealing and can be used to distinguish between mixed, layered and thermally annealed CO-CO2 ices. CO only affects the CO2 bending mode spectra in mixed ices below 50K under the current experimental conditions, where it exhibits a single asymmetric band profile in intimate mixtures. In all other ice morphologies the CO2 bending mode shows a double peaked profile, similar to that observed for pure solid CO2. Conversely, CO2 induces a blue-shift in the peak-position of the CO stretching vibration, to a maximum of 2142 cm-1 in mixed ices, and 2140-2146 cm-1 in layered ices. As such, the CO2 bending mode puts clear constraints on the ice morphology below 50K, whereas beyond this temperature the CO2 stretching vibration can distinguish between initially mixed and layered ices. This is illustrated for the low-mass YSO HH46, where the laboratory spectra are used to analyse the observed CO and CO2 band profiles and try to constrain the formation scenarios of CO2.

Accepted in A&A

References in corpus (6)

• A 3-5 micron VLT spectroscopic survey of embedded young low mass stars I: Structure of the CO ice
• Ices in the edge-on disk CRBR 2422.8-3423: Spitzer spectroscopy and Monte Carlo radiative transfer modeling
• Spitzer Space Telescope Spectroscopy of Ices toward Low Mass Embedded Protostars
• A 3-5$\mu$m VLT spectroscopic survey of embedded young low mass stars II; OCN${}^{-}$
• High Resolution 4.7 um Keck/NIRSPEC Spectra of Protostars. II: Detection of the 13CO Isotope in Icy Grain Mantles
• Gas-phase H2O and CO2 toward massive protostars

Cited by in corpus (25)

• Photochemistry and astrochemistry: photochemical pathways to interstellar complex organic molecules
• An Ice Age JWST inventory of dense molecular cloud ices
• The c2d Spitzer spectroscopic survey of ices around low-mass young stellar objects II: CO2
• Spitzer IRS Observations of Class I/II Objects in Taurus: Composition and Thermal History of the Circumstellar Ices
• CORINOS I: JWST/MIRI Spectroscopy and Imaging of a Class 0 protostar IRAS 15398-3359
• Quantification of segregation dynamics in ice mixtures
• CO2 Ice toward Low-luminosity, Embedded Protostars: Evidence for Episodic Mass Accretion via Chemical History
• LIDA - The Leiden Ice Database for Astrochemistry
• A survey of H${}_2$O, CO${}_2$ and CO ice features towards background stars and low mass YSOs using AKARI
• Band profiles and band strengths in mixed H2O:CO ices
• The Nature of Carbon Dioxide Bearing Ices in Quiescent Molecular Clouds
• Ice chemistry in embedded young stellar objects in the Large Magellanic Cloud
• Ice chemistry in massive Young Stellar Objects: the role of metallicity
• JWST observations of ${}^{13}$CO${}_2$ ice: Tracing the chemical environment and thermal history of ices in protostellar envelopes
• Anomalous CO2 Ice Toward HOPS-68: A Tracer of Protostellar Feedback
• JOYS+ study of solid state ${}^{12}$C/${}^{13}$C isotope ratios in protostellar envelopes: Observations of CO and CO${}_2$ ice with JWST
• Mid-IR and VUV Spectroscopic Characterisation of Thermally Processed and Electron Irradiated CO2 Astrophysical Ice Analogues
• On The Photodesorption of CO${}_2$ Ice Analogues: The Formation of Atomic C in The Ice and the Effect of The VUV Emission Spectrume
• Spectroscopic measurements of CH${}_3$OH in layered and mixed interstellar ice analogues
• The formation of CO${}_2$ through consumption of gas-phase CO on vacuum-UV irradiated water ice
• Carbonates and ices in the $z=0.89$ galaxy-absorber towards PKS 1830-211 and within star-forming regions of the Milky Way
• A fast machine learning tool to predict the composition of astronomical ices from infrared absorption spectra
• Study of the Inner Structure of the Molecular Torus in IRAS 08572+3915 NW with Velocity Decomposition of CO Rovibrational Absorption Lines
• Detection of CO${}_2$ ice in the planetary nebula NGC 6302
• Molecule-specific diffusion and desorption of interstellar ices on carbonaceous dust