Teorie agregátů fotosyntetických molekul: spektroskopie, struktura, přenosové jevy

Title: Theory of aggregates of photosynthetic molecules: spectroscopy, structure, transport phenomena Author: Ján Lalinský Institute: Institute of Physics of Charles University Supervisor of the master thesis: RNDr. Tomáš Mančal, PhD., Institute of Physics of Charles University Abstract. A theory of absorption of light in an isotropic solution of molecules was formulated on the basis of electromagnetic theory of par- ticles with attention to relativistic nature of their interaction and its im- pact on the spectrum of circular dichroism. Calculations of the absorption spectra of simple systems were performed to demonstrate the properties of the mathematical model. Also calculations of the absorption spectra of the models of the bacteriochlorophyll dimer which were proposed as possible basic unit in the lamellar model of the interior of a chlorosome were performed. The experimental spectra of solution of non-aggregated bacteriochlorophyll were used to fit the parameters of the mathematical model of the molecule and for these parameters the spectra of the pro- posed models of a dimer were calculated. It has been found that the new non-electrostatic terms in the description of the mutual interaction of the parts of the molecule are negligible for calculations of ordinary absorption spectrum, but they have...Název práce: Teorie agregátů fotosyntetických molekul: spektroskopie, struktura, přenosové jevy Autor: Ján Lalinský Ústav: Fyzikální Ústav Univerzity Karlovy Vedoucí diplomové práce: RNDr. Tomáš Mančal, PhD., Fyzikální Ústav Univerzity Karlovy Abstrakt. Teorie absorpce světla v izotropním roztoku molekul byla for- mulována na základě elektromagnetické teorie částic s přihlédnutím k rela- tivistické povaze jejich interakce a jejímu dopadu na spektrum cirkulárního dichroizmu. Byly provedeny výpočty absorpčních spekter jednoduchých systémů pro demonstraci vlastností matematického modelu. Také byly provedeny výpočty spekter modelů dimeru bakteriochlorofylů, které byly navrženy jako možná základní jednotka v lamelárním modelu vnitřní struk- tury chlorozomu. Experimentální spektra roztoku neagregovaného bakteri- ochlorofylu byla použita pro nastavení parametrů matematického modelu molekuly a pro tyto parametry byla spočtena spektra navržených modelů dimeru. Bylo zjištěno, že nové neelektrostatické členy v popisu vzájemné interakce částí molekuly jsou zanedbatelné pro výpočet obyčejného ab- sorpčního spektra, ale mají silný vliv na spektrum cirkulárního dichroizmu. Protože prezentovaný model popisuje vazbu elektronů a...Institute of Physics of Charles UniversityFyzikální ústav UKFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Bimetalni Ir-Al Schottkyjevi spojevi na GaAs

We report on novel Ir-Al/GaAs Schottky contact systems based on sequentially evaporated Ir-Al bimetallic multilayers. Electrical and thermal stability of these contact systems are investigated by I- V measurements and Auger depth profiling method. An increase of the barrier height with annealing temperature has been indicated for all Schottky contacts. A model of the barrier height enhancement based on a solid phase epitaxy of a graded AlxGa1-xAs layer at the interface at elevated temperatures was used to explain the electrical and the thermal stability of the contacts. A method of controlling of the barrier height and of the thermal stability of the Ir-Al/n-GaAs interface is proposed.Opisuju se novi Ir-Al/GaAs Schottkyjevi spojevi dobiveni uzastopnim naparavanjem Ir-Al bimetalnih slojeva. Električna i toplinska stabilnost spojeva ispituje se I −V mjerenjima i Augerovim dubinskim profiliranjem. Opaženo je povećanje barijere s povećanjem temperature otpuštanja. Za objašnjenje električne i toplinske stabilnosti spojeva, primijenjen je model povećanja barijere zasnovan na čvrstofaznoj epitaksiji AlxGa1−xAs sloja na granici spoja. Predložen je model upravljanja visinom barijere i toplinske stabilnosti granice Ir-Al/n-GaAs

Bimetalni Ir-Al Schottkyjevi spojevi na GaAs

We report on novel Ir-Al/GaAs Schottky contact systems based on sequentially evaporated Ir-Al bimetallic multilayers. Electrical and thermal stability of these contact systems are investigated by I- V measurements and Auger depth profiling method. An increase of the barrier height with annealing temperature has been indicated for all Schottky contacts. A model of the barrier height enhancement based on a solid phase epitaxy of a graded AlxGa1-xAs layer at the interface at elevated temperatures was used to explain the electrical and the thermal stability of the contacts. A method of controlling of the barrier height and of the thermal stability of the Ir-Al/n-GaAs interface is proposed.Opisuju se novi Ir-Al/GaAs Schottkyjevi spojevi dobiveni uzastopnim naparavanjem Ir-Al bimetalnih slojeva. Električna i toplinska stabilnost spojeva ispituje se I −V mjerenjima i Augerovim dubinskim profiliranjem. Opaženo je povećanje barijere s povećanjem temperature otpuštanja. Za objašnjenje električne i toplinske stabilnosti spojeva, primijenjen je model povećanja barijere zasnovan na čvrstofaznoj epitaksiji AlxGa1−xAs sloja na granici spoja. Predložen je model upravljanja visinom barijere i toplinske stabilnosti granice Ir-Al/n-GaAs

Piezoelektrická analýza saw snímača pomocou metódy konečných prvkov

In this contribution modeling and simulation of surface acoustic waves (SAW) sensor using finite element method will be presented. SAW sensor is made from piezoelectric GaN layer and SiC substrate. Two different analysis types are investigated - modal and transient. Both analyses are only 2D. The goal of modal analysis, is to determine the eigenfrequency of SAW, which is used in following transient analysis. In transient analysis, wave propagation in SAW sensor is investigated. Both analyses were performed using FEM code ANSYS.Príspevok sa zaoberá modelovaním a simuláciou SAW snímača, ktorý využíva šírenie povrchových vĺn, pričom na simulovanie sa využíva metóda konečných prvkov. SAW snímač je zložený z piezoelektrickej GaN vrstvy a z SiC substrátu. Vyšetrované sú dva typy analýz - modálna a prechodová. Cieľom modálnej analýzy je určiť vlastnú frekvenciu SAW snímača, ktorá je následne využitá v prechodovej analýze. V prechodovej analýze sa vyšetruje šírenie sa povrchovej vlny v SAW snímači. Obe analýzy sú realizované v MKP programe ANSYS

Piezoelectric fem analysis of surface acoustic wave sensor

The paper is focused on modeling and simulation of surface acoustic wave devices using finite element method, especially by code ANSYS. SAW sensor is made of piezoelectric GaN layer, in which the Rayleigh waves are generated, and of SiC substrate. Full 3D model of SAW sensor is investigated, where mechanical material model of GaN is considered to be transversally isotropic. Two different analyses are performed: modal and full transient. Modal analysis is performed to determine the speed of the Rayleigh waves in piezoelectric material and also in order to determine the interdigital transducer eigenfrequency, which is used in next transient analysis as electric frequency of excitation. The second analysis is the transient analysis, where the goal is to compare voltage on input and output interdigital transducer as well as wave propagation delay

New detectors for low-energy BSE

Backscattered electrons (BSE) are mostly used to study the specimen’s topography. Nowadays, low energy (units of keV) electron beam imaging is often necessary for example for the research of nanomaterials, biomaterials or semiconductors. Because BSE detectors are mostly non-accelerating or low-accelerating, electrons with approximately the same energy as primary beam (PB) have to be detected. Therefore, BSE detectors need to become optimized for such low-energy electrons. For the scintillation detectors, the biggest problem probably lies in the scintillator. Semiconductor detectors aren’t studied in this work. Cerium activated bulk single crystals of yttrium aluminium garnet (YAG:Ce)Ce(X):Y(3-X)Al(5)O(12) are widely used as scintillators for the detection of high-energy backscattered electrons (BSE). However, commonly used YAG:Ce single crystal strongly loses its light yield (LY) with the decrease of the PB energy. As possible available alternatives for this application, bulk single crystals of yttrium aluminium perovskite (YAP:Ce) Ce(x)Y(1-X)AlO(3) and CRY018 can be predicted. However, similar LY drop can be expected also with these scintillators

Design of internal CRM system for Memos Software, s.r.o.

Tato práce se zabývá návrhem interního CRM systému pro společnost Memos Software, který bude vycházet z již vyvinutého řešení. Je zapotřebí analyzovat firemní procesy a hlavní potřeby podniku a navrhnout takovou aplikaci, která by pokryla požadovanou funkcionalitu a pomohla obchodníkům podniku zkvalitnit jejich práci. Toto téma jsem si vybral proto, že ve jmenované firmě mám tento úkol přímo na starosti, takže se nebudu pokoušet navrhnout systém na papír, nicméně se budu opírat o praktické zkušenosti

Teorie agregátů fotosyntetických molekul: spektroskopie, struktura, přenosové jevy

Title: Theory of aggregates of photosynthetic molecules: spectroscopy, structure, transport phenomena Author: Ján Lalinský Institute: Institute of Physics of Charles University Supervisor of the master thesis: RNDr. Tomáš Mančal, PhD., Institute of Physics of Charles University Abstract. A theory of absorption of light in an isotropic solution of molecules was formulated on the basis of electromagnetic theory of par- ticles with attention to relativistic nature of their interaction and its im- pact on the spectrum of circular dichroism. Calculations of the absorption spectra of simple systems were performed to demonstrate the properties of the mathematical model. Also calculations of the absorption spectra of the models of the bacteriochlorophyll dimer which were proposed as possible basic unit in the lamellar model of the interior of a chlorosome were performed. The experimental spectra of solution of non-aggregated bacteriochlorophyll were used to fit the parameters of the mathematical model of the molecule and for these parameters the spectra of the pro- posed models of a dimer were calculated. It has been found that the new non-electrostatic terms in the description of the mutual interaction of the parts of the molecule are negligible for calculations of ordinary absorption spectrum, but they have..

Design of eWay-CRM pre-sales methodology

This work is related to design of eWay-CRM pre-sales methodology. It is based on world and domestic available approaches and existing models in eWay System, s.r.o