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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 693738.0, MPI für Astronomie / Publikationen_mpia
Analogs of solid nanoparticles as precursors of aromatic hydrocarbons
Authors:Gadallah, K. A. K.; Mutschke, H.; Jäger, C.
Date of Publication (YYYY-MM-DD):2013
Title of Journal:Astronomy and Astrophysics
Start Page:id. A12 (9 pp)
Audience:Not Specified
Abstract / Description:Context. Aromatic =CH and C=C vibrational bands have been observed within shocked interstellar regions, indicating the presence of aromatic emission carriers such as PAHs, which may have been created from adjacent molecular cloud material by interaction with a shock front. <BR /> Aims: We investigate the evolution of the aromatic =CH and C=C vibrational modes at 3.3 and 6.2 μm wavelength in heated HAC materials, PAHs and mixed PAHs and HACs, respectively, aiming at an explanation of the evolution of carbonaceous dust grains in the shocked regions. <BR /> Methods: Materials used in these analogs (HAC and PAH materials) were prepared by the laser ablation and the laser pyrolysis methods, respectively. The transmission electron microscopy (TEM) in high-resolution mode was used as an analytical technique to characterize the aromatic layers in HACs. Spectroscopic analysis was prformed in the mid-IR range. <BR /> Results: A remarkable destruction of aliphatic structures in HACs has been observed with the thermal processing, while aromatic structures become dominating by increasing the diameters of the graphene layers. The aromatic bands at 3.3 and 6.2 μm, observed in the laboratory spectra of PAHs and of the combination of the PAHs and HAC materials, are also clearly observed in the spectrum of the heated HACs. These bands agree with those of aromatic bands observed in astronomical observations. <BR /> Conclusions: Aromatization of HACs could be a pre-stage in the decomposition process of hydrocarbons that form PAH-clusters in such hot interstellar medium.
Free Keywords:astrochemistry; shock waves; methods: laboratory; dust; extinction; infrared: ISM; ISM: supernova remnants
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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