Abstract
The modelling of molecular excitation and dissociation processes relevant to astrochemistry requires the validation of theories by comparison with data generated from laboratory experimentation. The newly commissioned Ice Chamber for Astrophysics-Astrochemistry (ICA) allows for the study of astrophysical ice analogues and their evolution when subjected to energetic processing, thus simulating the processes and alterations interstellar icy grain mantles and icy outer Solar System bodies undergo. ICA is an ultra-high vacuum compatible chamber containing a series of IR-transparent substrates upon which the ice analogues may be deposited at temperatures of down to 20 K. Processing of the ices may be performed in one of three ways: (i) ion impacts with projectiles delivered by a 2 MV Tandetron-type accelerator, (ii) electron irradiation from a gun fitted directly to the chamber, and (iii) thermal processing across a temperature range of 20–300 K. The physico-chemical evolution of the ices is studied in situ using FTIR absorbance spectroscopy and quadrupole mass spectrometry. In this paper, we present an overview of the ICA facility with a focus on characterising the electron beams used for electron impact studies, as well as reporting the preliminary results obtained during electron irradiation and thermal processing of selected ices.Graphic
Highlights
The modelling of intense excitation processes in lowtemperature ices has found applications in a wide variety of fields [1], but in molecular astrophysics where such processes may lead to novel chemistry within the ice structure [2,3,4,5]
The recently commissioned Ice Chamber for Astrophysics-Astrochemistry (ICA), hosted by the Institute for Nuclear Research (Atomki) in Debrecen, is one such facility which is able to simulate various astrophysical environments and quantitatively analyse the physico-chemical changes occurring in deposited astrophysical ice analogues as a result of energetic processing
We present the results of the electron irradiation of amorphous methanol (CH3OH) ice at 20 K and the thermal processing of an ice mixture composed of water (H2O) and sulphur dioxide (SO2) in order to further demonstrate the ability of the set-up to provide data which may be useful to the astrophysical and astrochemical modelling communities
Summary
The modelling of intense excitation processes in lowtemperature ices has found applications in a wide variety of fields [1], but in molecular astrophysics where such processes may lead to novel chemistry within the ice structure [2,3,4,5]. Induced chemical reactions may occur in all astrophysical settings where temperatures are high enough to overcome the relevant activation energy barriers [13] This is especially important in the contexts of comets and icy outer Solar System moons, where such chemistry is known to be prevalent, and leads to the formation of complex molecules of astrobiological relevance. The importance of characterising the electron irradiation and thermal processing leading to interstellar and outer Solar System ice chemistry is apparent. We present the results of the electron irradiation of amorphous methanol (CH3OH) ice at 20 K and the thermal processing of an ice mixture composed of water (H2O) and sulphur dioxide (SO2) in order to further demonstrate the ability of the set-up to provide data which may be useful to the astrophysical and astrochemical modelling communities
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