Modeliranje elektronske gostote v tridimenzionalnih fazah termotropnih tekočih kristalov

diplomski seminar na študijskem programu 1. stopnje Fizika

Martin Vogrin (Author), Nataša Vaupotič (Mentor)

Abstract

V diplomskem seminarju predstavimo analizo dolžine in razvejanosti ogljikovodikovih repov tekoče kristalnih molekul ter optične čistosti na stabilnost tridimenzionalnih tekoče kristalnih faz. Predstavimo strukturno analizo vzorcev z optično mikroskopijo med prekrižanima polarizatorjema, rentgenskim sipanjem in diferencialno dinamično kalorimetrijo, s katerimi identificiramo strukture znotraj tekoče kristalnih faz. Na podlagi izkušenj z urejanjem molekul pri višjih in nižjih temperaturah in podatkom o simetriji osnovne celice predpostavimo modelske elektronske gostote in jih uporabimo za rekonstrukcijo elektronske gostote za kubični fazi z $Ia3d$ in $Im3m$ simetrijama ter za tetragonalno fazo z $I4_122$ simetrijo. Iz faz, opaženih pri višjih in nižjih temperaturah, sklepamo tudi o urejanju molekul v obravnavanih tridimenzionalnih fazah.

Keywords

diplomski seminarji;fizika;termotropni tekoči kristali;rentgensko sipanje;rekonstrukcija elektronske gostote;teoretično modeliranje elektronske gostote;kubične faze;tetragonalne faze;

Data

Language:	Slovenian
Year of publishing:	2014
Typology:	2.11 - Undergraduate Thesis
Organization:	UM FNM - Faculty of Natural Sciences and Mathematics
Publisher:	[M. Vogrin]
UDC:	53(043.2)
COBISS:	20862472
Views:	328
Downloads:	16
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	Modeling of electron densities in three-dimensional phases of thermotropic liquid crystals
Secondary abstract:	In this work we present a systematic study of the effect of length and branching of the aliaphatic tails of liquid crystal molecules and optical purity on the stability of three dimensional liquid crystal phases. We present structural analysis with optical microscopy between crossed polarizers, x-ray scattering and differential scanning calorimetry and from the results we identify structures of liquid crystal phases. From the experience on the molecular arrangement at lower and higher temperatures we construct theoretical electron density models and use them to reconstruct the electron densities for cubic phases with the $Ia3d$ and $Im3m$ symmetries and a tetragonal phase with the $I4_122$ symmetry. In addition, we deduce the molecular arrangement in the investigated phases from the structure of higher and lower temperature phases.
Secondary keywords:	physics;thermotropic liquid crystals;x-ray scattering;electron density reconstruction;theoretical modeling of electron densities;cubic phases;tetragonal phases;
Type (COBISS):	Final seminar paper
Thesis comment:	Univ. v Mariboru, Fak. za naravoslovje in matematiko, Oddelek za fiziko
Pages:	III, 24 f.
ID:	12531388