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Design and synthesis of surface architectures on fluorescent nanodiamonds
Havlík, Jan ; Kotek, Jan (advisor) ; Lang, Kamil (referee) ; Štěpánek, František (referee)
anks to their unique properties and high biocompatibilities, fluorescent nanodiamonds are promising representatives of modern carbon nanomaterials with a broad range of applications. Nevertheless, their wider use is limited because of weak fluorescence intensity and low colloidal stability in the biological environment. e optimization of treatment procedures and development of new suitable surface designs is therefore critically needed. In this study, several key steps for fluorescent nanodiamond treatment have been optimized, leading to both a substantial increase in fluorescence intensity and to significantly lower surface damage caused by graphitization. Further, a new high-throughput irradiation technique was developed. e influence of surface chemistry on the fluorescence parameters was studied using partial fluorination of the functional groups on the nanodiamond surface. A novel method which significantly affects the interaction of nanodiamonds with biological systems by increasing of the homogeneity and circularity was developed. e potential of nanodiamonds for future medical and biological research was demonstrated on particles with complex surface architectures that enabled targeting and therapy of tumor cells. Moreover, a strong and highly selective affinity of fibroblast growth factors to diamond...
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Laser spectroscopy of crystalline and nanocrystalline diamond
Zukerstein, Martin ; Trojánek, František (advisor)
The aim of this thesis is a study of NV centres in crystalline and nanocrystalline diamond by laser spectroscopy methods. In the theoretical part we discuss the laser spectroscopy methods, the studied material - diamond and the NV colour centres. In the experimental part we discuss the influence of nanoparticle size on luminescence spectra. We measure the luminescence of samples at room and also at low temperatures depending on the intensity and wavelength of the excitation. We study the photo-conversion of negatively charged state of NV centres to the neutral in detail. We make the time resolved measurements of the luminescence on streak camera for characterization the dynamical properties of the studied samples. The result is the comparison of lifetimes of the states in NV centres in selected samples.
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Comparative study on functionalization of NCD films with amine groups
Artemenko, Anna ; Kozak, Halyna ; Stuchlík, Jiří ; Biederman, H. ; Kromka, Alexander
Two plasma-based processes for functionalization of oxygen or hydrogen terminated NCD surfaces with amino groups were compared. The first process was based on deposition of thin (8 nm) amine containing plasma polymer by RF magnetron sputtering of Nylon target in Ar/N-2 working gas mixture. RF plasma treatment in NH3 for 10 minutes was used in the second process. The properties of NCD films before and after amination were characterized by scanning electron microscopy (SEM), wettability measurements, spectral ellipsometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and current-voltage (I-V) measurements. The presence of nitrogen (and thus amino groups) on the surface was confirmed by XPS measurements in both cases. The obtained results indicated that NCD surface functionalization from amine containing plasma polymer by RF magnetron sputtering is an alternative technological solution for successful functionalization of diamond surfaces for biosensor applications.
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Correlated microscopy of electronic and material properties of graphene grown on diamond thin films
Rezek, Bohuslav ; Čermák, Jan ; Varga, Marián ; Tulic, S. ; Skákalová, V. ; Waitz, T. ; Kromka, Alexander
In this work we compare growth of graphene on diamond thin films that enable large area processing. We use films with different crystal size and surface roughness to obtain deeper insight into formation and properties of GoD. The diamond films are coated by a nm thin sputtered Ni layer and heated to 900°C in a forming gas atmosphere (H2/Ar) to initiate catalytic thermal CVD process. The samples are cleaned from residual Ni after the growth process. We employ scanning electron microscopy, Raman micro-spectroscopy and Kelvin probe force microscopy to correlate material, structural, and electronic properties of graphene on diamond. We show how grain size and grain boundaries influence graphene growth and material and electronic properties. For instance we show that the grain boundaries (with non-diamond carbon phases) in diamond films have an important role. They influence the electronic properties and they are beneficial for forming graphene on diamond higher quality.
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Spatially separated HOMO/LUMO at interface of polypyrrole physisorbed on oxidized nanodiamond facets
Matunová, Petra ; Jirásek, Vít ; Rezek, Bohuslav
Nanodiamond particles (NDs) have recently risen in popularity owing to their unique and perspective properties. Merging NDs with organic molecules, such as polypyrrole (PPy), into hybrid organic-semiconductor functional systems gives rise to potential applications in photovoltaics (PV), which is supported by prior experimentally observed charge transfer between bulk diamond and PPy. This work focuses on the most relevant (111) and (100) O-terminated ND facets with different coverage of surface terminating oxygens in ether, epoxide, ketone, and peroxide positions. We use density functional theory (DFT) computations employing B3LYP functional and 6-31G(d) basis set. Energetically the most favorable oxidized ND facets were further optimized with PPy in physisorbed configurations. Analysis of geometry, binding energy, HOMO-LUMO gap, and charge transfer was done on the relaxed PPy-ND structures. Multiple hydrogen bonds are formed between PPy amino groups and O atoms on ND surface.
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Linear Accelerator Input Beam Data Collection for DIAMOND Calculation Systém Setup
KRÁKORA, Martin
The first chapter of the theoretical part of my bachelor's thesis is focused on the theme of radiotherapy in general as well as to its history. Radiotherapy is a young medical field which treats both malignant and non-malignant diseases by ionizing radiation. The roots of this discipline go back to the beginning of the 20th century, when German physicist Wilhelm Conrad Rontgen discovered X-rays. These rays started to be used in the treatment of tumorous diseases; the first case of tumour elimination by these rays was described in 1896. The second theoretical chapter outlines the types of radiotherapy and their clinical applications. The first type of radiotherapy is curative (radical), which is the primary choice for treatment of tumours, with the aim to eradicate the tumour completely and cure the patient. Another type of radiotherapy is adjuvant. This is a "securing" method, indicated in case of assumption that there are still microscopic tumour remains in the patient's body. There is also neoadjuvant radiotherapy, so-called preoperative. It is applied before the medical procedure when it is necessary to reduce the size of the tumour. Another clinically applied type is radiotherapy with palliative intent. This treatment is indicated to patients whose disease is incurable and serve to remove or alleviate the symptoms. The last type is non-tumorous radiotherapy. This method of treatment is used for non-tumorous diseases and it is always the method of the last resort. The following chapter discusses the theme of radiotherapeutic irradiator. These devices include simulator which simulates the irradiation plan and is very important for planning and control in radiotherapy. Linear accelerators are the most often tools used for irradiation. These accelerators use high-frequency beam of photons or electrons for irradiation. Other devices used in radiotherapy include cobalt and cesium irradiators. The fourth chapter deals with planning in radiotherapy. Irradiation plan, which must be approved by a doctor, is put together in the process of planning. This plan is approved in case when the created combination of irradiation fields achieves the most accurate covering of the target volume by a required dose, and at the same time healthy tissues and organs are spared as much as possible. This chapter also mentions the theme of phantoms that are very important for planning in radiotherapy. Phantoms were also used during the measurement within the practical part of the thesis. The fifth chapter is devoted to irradiation techniques used in radiotherapy. All basic techniques used for irradiation are described here one-field irradiation technique, which is the simplest one, two-field irradiation, i.e. contralateral, convergent or tangential techniques. Also three-field irradiation technique the T and Y techniques, as well as the four-field technique BOX and Crossfire techniques. The most complex techniques include five and more fields where three-dimensional conformational radiotherapy is used. The last chapter describes individual planning systems used at the Department of Oncology of České Budějovice Hospital, with which the objectives of the practical part of the bachelor's thesis were achieved. These planning systems include Mephysto mc2, Diamond and Eclipse programs. Independent measurements were carried out within the practical part of the bachelor's thesis, on the basis of which the following hypothesis was confirmed: "A procedure implemented in compliance with methodology No. 4 can shorten the time of measuring of parameters of ionizing radiation beams from linear accelerator to be entered into the DIAMOND computing system." The aim of the thesis was to get data files for entering the source of ionizing radiation (linear accelerator) into the DIAMOND computing system. This objective was achieved and the respective data files are presented in the chapter of Results (the whole version is attached to this thesis on a CD).
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Femtosecond laser spectroscopy of diamond
Bažíková, Sára ; Malý, Petr (advisor) ; Preclíková, Jana (referee)
Due to its extraordinary features and wide bandwidth (5.47 eV), diamond is a very promising material in the field of optoelectronics. By absorbing ultraviolet light, excited charge carriers - electrons and holes - are created in the diamond, which can create excitons due to mutual Coulomb interaction. For low temperatures and high concentrations of photoexcitated carriers, carriers can condense into electron-hole droplets and form an electron-hole liquid. The aim of this diploma thesis is to follow up with previous research at the department and to examine the dynamics of electron-hole liquid in bulk diamond at low temperatures. Using femtosecond laser spectroscopy, we investigate the influence of excitation wavelengths on the dynamics of electron-hole liquid condensation.
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Laser spectroscopy of crystalline and nanocrystalline diamond
Zukerstein, Martin ; Trojánek, František (advisor) ; Preclíková, Jana (referee)
The aim of this thesis is a study of NV centres in crystalline and nanocrystalline diamond by laser spectroscopy methods. In the theoretical part we discuss the laser spectroscopy methods, the studied material - diamond and the NV colour centres. In the experimental part we discuss the influence of nanoparticle size on luminescence spectra. We measure the luminescence of samples at room and also at low temperatures depending on the intensity and wavelength of the excitation. We study the photo-conversion of negatively charged state of NV centres to the neutral in detail. We make the time resolved measurements of the luminescence on streak camera for characterization the dynamical properties of the studied samples. The result is the comparison of lifetimes of the states in NV centres in selected samples.
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Multiphoton absorption of ultrafast laser pulse
Zukerstein, Martin ; Trojánek, František (advisor) ; Schmoranzerová, Eva (referee)
Nonlinear optics is constantly developing and in terms of future applications very perspective field of physics. With high-intensity pulsed lasers we are able to study interesting phenomena in matter that we cannot observe with common sources of light. The aim of this thesis is a study of the multiphoton absorption of high-intensity pulses in diamond using z-scan technique. It theoretically describes this nonlinear phenomenon using quantum theory. The next section author took a measurement of the two-photon absorption and found the two-photon absorption coefficients in different samples. Diamond was chosen as the sample material. This material has absolutely unique properties that rank it highly in future applications for optoelectronic devices.
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Studium optických nelinearit v polovodičích a polovodičových nanostrukturách
Kozák, Martin ; Trojánek, František (advisor) ; Herynková, Kateřina (referee) ; Kužel, Petr (referee)
This Ph.D. thesis is focused on the study of optical nonlinearities and dynamics of excited charge carriers in monocrystalline diamond, nanocrystalline diamond and silicon. The dynamics of high density carriers in bulk diamond is investigated in detail (the transition from excitons and free carriers to electron-hole liquid or plasma). We study the picosecond dynamics of electron-hole liquid condensation using several techniques of time-resolved optical spectroscopy and demonstrate its evaporation by femtosecond laser pulses. We also propose two new optical techniques for measurement of lifetime, diffusion coefficient and surface recombination velocity of excitons in diamond. The results obtained by these techniques are described theoretically using diffusion equation and compared with the results obtained by the transient grating diffraction measurement. Further we study two- and three- photon absorption and nonlinear refractive index in diamond. In nanocrystalline diamond we study the second and third harmonic generation and its physical origin. In superlattices of silicon nanocrystals in SiO2 matrix we investigate the nonlinear transient absorption dynamics and carrier diffusion.
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