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Identifier

000372146

Title

Σύνθεση και φασματοσκοπικός χαρακτηρισμός θολινών ως μοντέλων αερολυμάτων της ατμόσφαιρας του Τιτάνα

Alternative Title

Synthesis and spectroscopic characterization of tholins as model aerosols in the atmosphere of Titan

Author

Καραφάς, Εμμανουήλ Στ.

Thesis advisor

Σπύρος, Απόστολος

Abstract

The aim of the present MSc. dissertation was the synthesis and structural analysis of Titan’s atmospheric organic aerosol analogues, namely tholins. The interest for Titan’s atmospheric chemistry stems from compositional similarities between the largest Saturnian satellite and prebiotic Earth. To this purpose, two complementary experimental techniques were employed: a. Thermostated Photochemical Reactor/Laser Assisted Chemical Vapour Deposition (TPCR/LACVD) and b. Discharge-Flow Plasma Vapour Deposition (DFPVD). The former method was proved be the more efficient route for tholins synthesis in the laboratory. In both cases, tholins synthesis proceeded under controlled pressure (1 – 1100 Torr) and temperature (77 – 296 K) conditions. A combination of modern analytical methodologies, MALDI/TOF-MS, Raman, ATR/FTIR and NMR, were employed for the structural analysis and characterization of the synthesized tholin materials. MALDI/TOF-MS demonstrated the polymeric nature of tholin analogues showing a broad distribution of molecular weights in the range ~500 – 2800 amu. Raman, FTIR and NMR showed the presence of C-H, N-H, C-N, C=N and CN moieties in the polymer structure, as well as aromatic, vinyl and aliphatic structural subunits, revealing the increased chemical heterogeneity of tholin macromolecules. Analysis based on 2D NMR led to the suggestion of several possible chemical substructures consistent with the spectral data from MALDI/TOF-MS, Raman and ATR/FTIR techniques. Finally, sp² aromatic to total (aromatic and aliphatic) carbon ratios that were determined via Raman and NMR spectroscopy as a function of pressure were in good agreement. The latter information is essential for investigating and understanding the polymerization mechanism that results in tholins formation.

Language

Greek

Subject

Analytical spectroscopy

Astrobiology

LaserCo2

Polymers

Prebiotic earth

Αερολύματα

Αναλυτική φασματοσκοπία

Αστροβιολογία

Θολίνες