Residue from vacuum ultraviolet irradiation of benzene ices: Insights into the physical structure of astrophysical dust

Abstract

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Experimental Simulation of Titan's Stratospheric Photochemistry: Benzene (C6H6) Ices

“…Figure 1, Yoon et al., 2014). Previous experiments were performed under conditions (temperatures between 4 K and 19 K)/energy sources) relevant for the ISM, either to understate its fate under UV radiations (Rahul et al., 2020; Ruiterkamp et al., 2005) or ion bombardment (Callahan et al., 2013; Strazzulla & Baratta, 1991), or to identify its photo‐degradation pathways with the help of matrix‐isolated environment (Johnstone & Sodeau, 1991; Ruiterkamp et al., 2005). But none of these studies can be used as a reference for simulating Titan's low stratospheric environment.…”

N-graphene synthesized in astrochemical ices

“…1). Such a spectrum in the VUV is characteristic of aromatic derivatives [27]. Thus, both spectroscopic techniques provide compelling evidence that the residue synthesized by VUV irradiation contains aromatic molecules.…”

“…Residue from hydrocarbon ice irradiation was reported [24] to be fluffy and porous due to polymerization on carbon-rich ices [25] leading to micrometer-sized polymer layers [26]. In addition, the residues obtained by irradiating an aromatic (benzene) molecular ice were found to contain geometric shapes such as micron sized cubes and spheres, surrounded by nanoparticles [27]. The chemical analysis of the aromatic residues contained aromatic derivatives, and from biphenyls to polyphenyls [28], characteristic spectral signatures of aromatic derivatives were present in the vacuum ultraviolet (VUV) photoabsorption spectrum of the residue [27].…”

“…In addition, the residues obtained by irradiating an aromatic (benzene) molecular ice were found to contain geometric shapes such as micron sized cubes and spheres, surrounded by nanoparticles [27]. The chemical analysis of the aromatic residues contained aromatic derivatives, and from biphenyls to polyphenyls [28], characteristic spectral signatures of aromatic derivatives were present in the vacuum ultraviolet (VUV) photoabsorption spectrum of the residue [27]. Two possibilities for the composition of the residues can be discussed, (i) mixed aromatic/aliphatic organic nanoparticles (MAONs) as dust in the place of (ii) polycyclic aromatic hydrocarbons (PAH), based on space-based observations in the infrared [29,30].…”

Vacuum UV Photolysis of Benzene in Solid Nitrogen

“…Because of the thin atmosphere of Pluto, vacuum UV (VUV) photons and high-energy particles may reach the surface to modify the chemical compositions of the surface organic ices. In the recent two decades, numerous studies on UV or energetic particle treatments of pure C 6 H 6 ices − and C 6 H 6 diluted in solid matrices − have been reported. Identifying products produced from the irradiation of pure C 6 H 6 ice by IR spectroscopy is difficult because the interaction between the host C 6 H 6 and products is often strong, resulting in the largely shifted and/or broadened spectral lines of products.…”