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Title

Οπτικές ιδιότητες φωτοχρωμικών υλικών

Author

Καλαφατάκης, Κωνσταντίνος

Thesis advisor

Φαρσάρη, Μαρία

Reviewer

Καλπούζος, Κωνσταντίνος
Παπάζογλου, Δημήτριος

Abstract

The development of structures of nanometer and micrometer size over the last few years has given rise to research into new materials, so that the present structures to be improved. This need for improvement has driven the search for new materials which go through mechanical transformation when interacting with light. The macromolecular polymeric matrices with incorporated photochromic molecules belong to this category of materials. The present project studies the properties of such materials. In particular, thin polymeric films of PEMMA doped with the photochromic compound Spiropyran in various concentrations have been studied. The molecule of Spiropyran is transformed into Merocyanine when exposed to ultraviolet radiation and back to Spyropyran when exposed to visible radiation. In this study, the absorption spectra of the doped films have been taken and the maximum absorption wavelength corresponding to each of these thin films has been calculated. It has been found that in small concentrations of Spiropyran (less than 10%) the absorption coefficient increases almost in linearly with the concentration of the photochromic molecule; however saturation is observed at greater concentrations. Subsequently, the change of the refractive index between the non excited and excited state respectively of these thin films has been studied, as well as the way that refractive index is changing in terms of the concentrations of Spiropyran in polymeric film of PEMMA. The waveguiding experiment which has been set-up for this purpose measures with accuracy the refractive index (third decimal place) as well as the thickness of those thin films (accuracy ~ 0,3μm). The measurements have been carried out using visible and infrared lasers as sources of radiation. We have observed that refractive index is increasing with the increase of Spiropyran in the PEMMA.

Language

Greek

Subject

Light

Opthalmology

Pyrans

Spiro Compounds

Οφθαλμολογία

Πυράνια

Σπειροενώσεις

Issue date

2006-03-22