Carbonization in Titan Tholins: implication for low albedo on surfaces of Centaurs and trans-Neptunian objects

2015 ◽  
Vol 15 (3) ◽  
pp. 231-238 ◽  
Author(s):  
Chaitanya Giri ◽  
Christopher P. McKay ◽  
Fred Goesmann ◽  
Nadine Schäfer ◽  
Xiang Li ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Organic Material ◽  
Near Infrared ◽  
Proof Of Concept ◽  
Astronomical Observations ◽  
Polycyclic Aromatic ◽  
Large Polycyclic Aromatic Hydrocarbons ◽  
Characteristic Features ◽  
Complex Organic ◽  
Geometric Albedo

AbstractAstronomical observations of Centaurs and trans-Neptunian objects (TNOs) yield two characteristic features – near-infrared (NIR) reflectance and low geometric albedo. The first feature apparently originates due to complex organic material on their surfaces, but the origin of the material contributing to low albedo is not well understood. Titan tholins synthesized to simulate aerosols in the atmosphere of Saturn's moon Titan have also been used for simulating the NIR reflectances of several Centaurs and TNOs. Here, we report novel detections of large polycyclic aromatic hydrocarbons, nanoscopic soot aggregates and cauliflower-like graphite within Titan tholins. We put forth a proof of concept stating the surfaces of Centaurs and TNOs may perhaps comprise of highly ‘carbonized’ complex organic material, analogous to the tholins we investigated. Such material would apparently be capable of contributing to the NIR reflectances and to the low geometric albedos simultaneously.

scholarly journals Spectroscopy of Fullerenes, Fulleranes and PAHs in the UV, Visible and Near Infrared Spectral Range

2013 ◽  
Vol 9 (S297) ◽  
pp. 294-296 ◽  
Author(s):  
F. Cataldo ◽  
D. A. García-Hernández ◽  
A. Manchado ◽  
S. Iglesias-Groth
Keyword(s):  
Spectral Range ◽  
Aromatic Hydrocarbons ◽  
Near Infrared ◽  
Visible Spectral Range ◽  
Infrared Spectral Range ◽  
Higher Fullerenes ◽  
Infrared Spectral ◽  
Polycyclic Aromatic ◽  
Large Polycyclic Aromatic Hydrocarbons ◽  
Uv Visible

AbstractThe spectra of fullerenes C60 and C70, higher fullerenes C76, C78 and C84 and hydrogenated fullerenes (fulleranes) were studied in laboratory in the UV and in the visible spectral range and could be used for searching and recognizing these molecules in space. Furthermore, the radical cation spectra of all the mentioned fullerene series and also of a series of large and very large polycyclic aromatic hydrocarbons (PAHs) were generated in the laboratory and studied in the near infrared spectral range.

scholarly journals Site-Selective [2+2+n] Cycloadditions for Rapid, Scalable Access to Alkynylated Polycyclic Aromatic Hydrocarbons

2019 ◽  
Author(s):  
Gavin R. Kiel ◽  
Harrison Bergman ◽  
T. Don Tilley
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Structural Complexity ◽  
Building Blocks ◽  
Synthetic Methods ◽  
Proof Of Concept ◽  
Site Selectivity ◽  
Polycyclic Aromatic ◽  
Site Selective ◽  
Nanometer Regime

Polycyclic aromatic hydrocarbons (PAHs) are attractive synthetic building blocks for more complex conjugated nanocarbons, but their use for this purpose requires appreciable quantities of a PAH with reactive functional groups. Despite tremendous recent advances, most synthetic methods cannot satisfy these demands. Here we present a general and scalable [2+2+n] (n = 1 or 2) cycloaddition strategy to access PAHs that are decorated with synthetically versatile alkynyl groups and its application to seven structurally diverse PAH ring systems (thirteen new alkynylated PAHs in total). The critical discovery is the site-selectivity of an Ir-catalyzed [2+2+2] cycloaddition, which preferentially cyclizes tethered diyne units with preservation of other (peripheral) alkynyl groups. The potential for generalization of the site-selectivity to other [2+2+n] reactions is demonstrated by identification of a Cp<sub>2</sub>Zr-mediated [2+2+1] / metallacycle transfer sequence for synthesis of an alkynylated, selenophene-annulated PAH. The new PAHs are excellent synthons for macrocyclic conjugated nanocarbons. As a proof of concept, four were subjected to Mo catalysis to afford large, PAH-containing arylene ethylene macrocycles, which possess a range of cavity sizes reaching well into the nanometer regime. More generally, this work is a demonstration of how site-selective reactions can be harnessed to rapidly build up structural complexity in a practical, scalable fashion.

scholarly journals A Review on Carbon-rich Molecules in Space

2012 ◽  
Vol 10 (H16) ◽  
pp. 720-722 ◽  
Author(s):  
Franco Cataldo ◽  
D. Aníbal García-Hernández ◽  
Arturo Manchado
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Electronic Absorption ◽  
Aromatic Hydrocarbons ◽  
Electronic Absorption Spectra ◽  
Heavy Petroleum ◽  
Carbon Chains ◽  
Petroleum Fractions ◽  
Polycyclic Aromatic ◽  
Large Polycyclic Aromatic Hydrocarbons ◽  
Related Derivative

AbstractWe present and discuss carbon-rich compounds of astrochemical interest such as polyynes, acetylenic carbon chains and the related derivative known as monocyanopolyynes and dicyanopolyynes. Fullerenes are now known to be abundant in space, while fulleranes - the hydrogenated fullerenes - and other carbon-rich compounds such as very large polycyclic aromatic hydrocarbons (PAHs) and heavy petroleum fractions are suspected to be present in space. We review the synthesis, the infrared spectra as well as the electronic absorption spectra of these four classes of carbon-rich molecules. The existence or possible existence in space of the latter molecules is reported and discussed.

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