Unit:
Κατεύθυνση ΦυσικοχημείαLibrary of the School of Science
Author:
Tourlakis Georgios
Supervisors info:
Τσεκούρας Αθανάσιος, Επίκουρος Καθηγητής, Τμήμα Χημείας, ΕΚΠΑ
Original Title:
Μελέτη της αυθόρμητης πόλωσης λεπτών υμενίων προπανάλης και εστέρων σε χαμηλές θερμοκρασίες
Translated title:
Study of spontaneous polarization of thin films of propanal and esters at low temperatures
Summary:
In this thesis, the phenomenon of spontaneous polarization is studied which occurs when thin films of organic polar molecules are deposited onto a metallic substrate at low temperatures. The compounds examined were propanal, methyl acetate, ethyl acetate, propyl acetate, butyl acetate and amyl acetate. Depositions were carried out at temperatures ranging from 33 K to 135 K onto a polycrystalline platinum foil. The whole experiment was conducted inside a high vacuum chamber equipped with a quadrupole mass spectrometer and a Kelvin probe. Every cycle of measurements consisted of depositing each compound onto the substrate at the desired temperature, taking a starting voltage reading from the Kelvin probe, ramping up the temperature while continuing monitoring the voltage until it dropped to pre-deposition levels. The non-linear dependence of the surface potential on the deposition temperature was confirmed. The surface potential was found to be linearly dependant on the number of deposited molecules. The effect that the deposition temperature has on the degree of polarization was showed.
Main subject category:
Science
Keywords:
Spontaneous polarization, thin films, propanal, acetates, polarizability, surface potential
