Fullerenes and PAHs in space
نویسنده
چکیده
Theoretical, observational and laboratory work on the new form of carbon known as fullerenes and its hydrogenated forms (fulleranes) are reviewed. These molecules can be responsible of diffuse interstellar bands, the UV bump, a major feature in the extinction curves measured in many lines of sight in our Galaxy and other galaxies and the anomalous microwave emission detected in several regions of star formation,in molecular clouds and HII regions. Recent detections of fullerenes C60 and C70 in planetary nebulae of our Galaxy and in the Magallanic cloud render support to the hypothesis that fullerenes and fulleranes are carriers of these processes. Other potential agents of these emission and absorption processes are the polycyclic aromatic hydrocarbons (PAHs). We also review observational efforts to identify the most simple PAHs, naphthalene and anthracene, in regions of anomalous microwave emission.
منابع مشابه
Top-down formation of fullerenes in the interstellar medium.
Fullerenes have been recently detected in various circumstellar and interstellar environments, raising the question of their formation pathway. It has been proposed that they can form at the low densities found in the interstellar medium by the photo-chemical processing of large polycyclic aromatic hydrocarbons (PAHs). Following our previous work on the evolution of PAHs in the NGC 7023 reflect...
متن کاملThe electron density function of the Hückel (tight-binding) model
The Hückel (tight-binding) molecular orbital (HMO) method has found many applications in the chemistry of alternant conjugated molecules, such as polycyclic aromatic hydrocarbons (PAHs), fullerenes and graphene-like molecules, as well as in solid-state physics. In this paper, we found analytical expressions for the electron density matrix of the HMO method in terms of odd-powers of its Hamilton...
متن کاملFormation of Carbon Nanotube Based Gears: Quantum Chemistry and Molecular Mechanics Study of the Electrophilic Addition of o-Benzyne to Fullerenes, Graphene, and Nanotubes
Considerable progess has been made in recent years in chemical functionalization of fullerene molecules [see, for example: Taylor 93, and Diederich 96]. In some cases, the predominant reaction products are different from those obtained (using the same reactants) from polycyclic aromatic hydrocarbons (PAHs). One such example is the cycloaddition of o-benzyne to C60. It is well established that b...
متن کاملFormation of Pahs and Carbonaceous Solids in Gas-phase Condensation Experiments
Carbonaceous grains represent a major component of cosmic dust. In order to understand their formation pathways, they have been prepared in the laboratory by gas-phase condensation reactions such as laser pyrolysis and laser ablation. Our studies demonstrate that the temperature in the condensation zone determines the formation pathway of carbonaceous particles. At temperatures lower than 1700K...
متن کاملAn insight into the local aromaticities of polycyclic aromatic hydrocarbons and fullerenes.
In this work we quantify the local aromaticity of six-membered rings in a series of planar and bowl-shaped polycyclic aromatic hydrocarbons (PAHs) and fullerenes. The evaluation of local aromaticity has been carried out through the use of structurally (HOMA) and magnetically (NICS) based measures, as well as by the use of a new electronically based indicator of aromaticity, the para delocalizat...
متن کامل