The commissioning of the ALMA array and the next generation of space telescopes heralds the dawn of a new age of Astronomy, in which the role of chemistry in the interstellar medium and in star and planet formation may be quantified. A vital part of these studies will be to determine the molecular complexity in these seemingly hostile regions and explore how molecules are synthesised and survive. The current hypothesis is that many of these species are formed within the ice mantles on interstellar dust grains with irradiation by UV light or cosmic rays stimulating chemical reactions. However, such irradiation releases many secondary electrons which may themselves induce chemistry. In this article we discuss the potential role of such electron induced chemistry and demonstrate, through some simple experiments, the rich molecular synthesis that this may lead to.

Abstract:Infrared spectra of solid formamide are reported as a function of temperature.Solid formamide samples were prepared at 30 K and then annealed to higher temperatures 300 K with infrared transmission spectra being recorded over the entire temperature range. The NH2 vibrations of the formamide molecule were found to be particularly very sensitive to temperature change. The IR spectra revealed a phase change occurring in solid formamide between 155 K to 165 K. Spectral changes

Context. Enceladus, a small icy moon of Saturn, is one of the most remarkable bodies in the solar system. This moon is a geologically active object, and despite the lower temperatures on most of its surface, the geothermally heated south polar region presents geysers that spouts a plume made of water (∼90%), carbon dioxide, methane, ammonia, and methanol, among other molecules. Most of the upward-moving particles do not have the velocity to escape from the gravitational influence of the moon and fall back to the surface. The molecules in the ice are continuously exposed to ionizing radiation, such as UV and X-rays photons, cosmic rays, and electrons. Over time, the ionizing radiation promotes molecular bond rupture, destroying and also forming molecules, radicals, and fragments. Aims. We analyse the processing of an ice mixture analogue to the Enceladus fallout ice in cold resurfaced areas (north pole) by 1 keV electrons. The main goal is to search for complex species that have not yet been detected in this moon, and to determine relevant physico-chemical parameters, such as destruction and formation cross-sections and the half-life of the studied molecules in the ice. Methods. The experiment consisted of the electron irradiation of an Enceladus-like ice mixture (H 2 O:CO 2 :CH 4 :NH 3 :CH 3 OH) in an ultra-high vacuum chamber at 20 K. The analysis was made by infrared spectrometry in the mid-infrared region (4000−800 cm −1 or 2.5−12.5 μm). Results. The absolute dissociation cross-sections of the parent molecules, the formation cross-section of daughter species, and the half-life of the parental species in a simulated Enceladus irradiation scenario were determined. Among the produced species, CO (carbon monoxide), OCN − (cyanate anion), HCONH 2 (formamide), and H 2 CO (formaldehyde) were tentatively detected.

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The Open University's repository of research publications and other research outputs Vacuum ultraviolet and infrared spectra of condensed methyl acetate on cold astrochemical dust analogs