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Title: Optical and Thermal Properties of Coffee and Caffeine
???metadata.dc.contributor.*???: Dr. Araya Asfaw
Ture, Kassahun
Keywords: Coffee;Caffeine;Fluorescence;Solventochromism;Thermal;UV/Vis
Issue Date: Jun-2005
Publisher: Addis Ababa University
Abstract: In this project, the thermal and optical properties of coffee and caffeine are investigated, Characteristics involved are solvatochromic effect, fluorescence, chemical structures (bonds) and thermal properties of both coffee and caffeine. The UV/Vis absorption band of caffeine in different solvents shows very small solvatochromic effect, indicating only local transitions of electrons. This founding is similar to that found for QM-calculations. Fluorescence measurements revealed no fluorescence emission by caffeine, but deactivation of fluorescien fluorescence intensity. However, simple correlation between the deactivation produced by caffeine and coffee on the fluorescence of fluorescein could not be drawn with out the detailed knowledge of other components. From FT-IR results, the fluorescence deactivation mechanism is found to incorporate carbonyl groups of both caffeine and coffee. The obseived thermal (TGA) results showed coffee is thermally unstable and decomposes steadly.This shows the inherent discrepancy of the temperature dependent measurement, which makes exact measurement of caffeine at various temperature intervals unrealistic, The DSC result shows crystallization, heat absoiption melting and heat release of coffee at various temperature regions.
Description: A Thesis Presented to The School of Graduate Studies The Faculty of Science Addis Ababa University In partial Fulfillment of the Requirements for the Degree of Master of Science in Physics.
Appears in Collections:Thesis - Physics

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