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Molecular Crystals for Nonlinear Optics - Salts of Nitrogen-containing Bases with Selenious Acid and Hypophosphorous Acid
Němcová, Tereza ; Matulková, Irena (advisor) ; Tyrpekl, Václav (referee)
In this bachelor thesis, systems of selenious acid and hypophosphorous acid with six organic bases (2-aminopyrimidine, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 2-aminoguanidine and biguanide) were studied as the source of new materials for nonlinear optics. The six prepared crystalline compounds were identified and characterized by vibrational spectroscopy and X-ray diffraction. Unfortunately, all prepared salts contain a centre of symmetry in their structures, and therefore none of them are suitable for nonlinear optics especially the second harmonic generation.
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Novel materials for nonlinear optics - salts and cocrystals of heteroaromatic bases
Kloda, Matouš ; Němec, Ivan (advisor) ; Gyepes, Róbert (referee)
The main issue of this master thesis is investigation of new compounds of aminopyrazine and 3-amino-1,2,4-triazine in consideration of their potential usage in the field of nonlinear optics. The focus of this thesis was finishing of characterisation of an adduct of aminopyrazine and boric acid prepared as a part of previous bachelor thesis, as well as preparation of salts and cocrystals combining 3-amino-1,2,4-triazine with selected acids. Prepared materials were characterised mainly by the means of vibrational spectroscopy and x-ray diffraction analysis. Prediction of nonlinear optical properties of selected molecules and interpretation of recorded vibrational spectra was based on quantum chemical calculations. Finally, measurements of second harmonic generation efficiency of selected powder samples were performed.
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Interpretation of the C=O band of modified diamond nanoparticles by means of DFT theory
Jirásek, Vít ; Kozak, Halyna ; Remeš, Zdeněk ; Kromka, Alexander
Diamond nanoparticles (DNPs) are an interesting class of nanomaterials, which has many unique properties. Their applications in medicine and molecular biology have been mentioned. The DNPs were reviewed in sense of their surface chemistry and a range of analytic techniques was pointed out. The experimental analysis can be enhanced by theoretical models based on the first principles. An approach to theoretical analysis of infrared spectra was introduced. As an example, a part of FTIR spectra of the oxidized DNPs was interpreted by means of the DFT theory. The calculation of the C=O stretch vibrational frequencies of carboxylic and anhydride groups on certain model clusters enabled to explain the shift and splitting of the measured spectral bands.
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