Electron Irradiation and Thermal Chemistry Studies of Interstellar and Planetary Ice Analogues at the ICA Astrochemistry Facility

TL;DR

This paper introduces the ICA Astrochemistry Facility, a laboratory setup for studying how interstellar and planetary ices evolve under energetic processing like electron irradiation and heating, aiding astrochemical models.

Contribution

The paper details the design and capabilities of the ICA facility, including its methods for simulating astrophysical ice processing and initial experimental results.

Findings

Electron beams characterized for astrochemical experiments

Preliminary data on ice chemistry changes under irradiation

Thermal processing effects observed on interstellar ice analogues

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.