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The recent discovery of 1-propanol (CH3CH2CH2OH) in the interstellar medium (ISM) is of tremendous interest since fatty alcohols have been proposed as constituents of proto-cell membranes. Motivated by this discovery, we present the laboratory mid-infrared (MIR) and vacuum ultraviolet (VUV) absorption spectra of 1-propanol ice under astrochemical conditions, mimicking an icy mantle on cold dust in the ISM. Both MIR and VUV spectra were recorded at ultrahigh vacuum of ∼10-9 mbar and at temperatures ranging from 10 K to sublimation. The morphology of the 1-propanol ice deposited at 10 K was amorphous. By warming the ice to temperatures of 140 K and above, with subsequent recording of IR spectra, we observe complete sublimation of 1-propanol molecules from the substrate around 170 K. No amorphous-to-crystalline phase change was observed upon warming to higher temperatures. Additionally, we observe the IR and VUV signatures of 1-propanol ice on the substrate well beyond its melting point (147 K). To the best of our knowledge, this is the first reported observation of a molecular ice staying well beyond its melting point under such conditions. This result shows that the morphology of icy mantles on ISM cold dust grains is more complex than previously thought. Our atomistic molecular dynamics simulations capture the experimental trends and shed light on the microscopic origin of this unusual phase behaviour of 1-propanol. [ABSTRACT FROM AUTHOR]

The fate of organometallic dust subjected to extreme conditions, especially the shock fronts, in the interstellar medium (ISM) has not been explored to date. Iron and cyclopentadiene, which have been found to be present in the ISM, are known to react and produce the organometallic compound ferrocene under terrestrial conditions. In our experiment we subjected ferrocene, a possible proxy of such dust, to ∼5.6 Mach (M) shock commensurate with conditions encountered in the ISM, leading to a temperature rise up to 7300 K within 2 ms. Analysis of the post-shock residue showed the presence of a α-Fe and Fe3C composite that responded to an external magnetic field. These results show that a non-magnetic dust composed of molecules containing transition metals undergoing shock processing in the ISM can dissociate and synthesize dust that is then magnetic. Such drastic transformations from non-magnetic to magnetic dust induced by shocks might be of importance in interstellar polarization. [ABSTRACT FROM AUTHOR]