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Intensity Normalization of Raman Spectra by Means of Various Internal Standards
Sláma, Vladislav ; Mojzeš, Peter (advisor) ; Procházka, Marek (referee)
The work deals with the testing of selected inorganic anions as internal standards for intensity normalization of Raman spectra. Using the concentration and temperature series of aqueous solutions of PO4 3- , (CH3)2AsO2 - , NO3 - a SO4 2- , impact of the spectral changes of the standard bands for reliability and accuracy of the intensity calibration was studied. Temperature and concentration series of the anion Raman spectra are then used to test normalization by means of the bands of stretching and deformation vibrations of water molecules. In addition, reliability and robustness of the calibration procedures exploiting different spectral parameters present in the Raman spectra of standards was tested. Results of the study reveal possible sources of artifacts and misinterpretations arising from insufficient understanding of the standard behavior due to changes of the physical and chemical parameters, or due to improper calibration procedure applied.
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Structure and selforganization of aggregates of photosynthetic molecules
Sláma, Vladislav ; Mančal, Tomáš (advisor) ; Duffy, Christopher (referee) ; Veis, Libor (referee)
In this work we demonstrate how quantum chemistry (QC) methods and molecular dynamics (MD) simulations can be used in combination with Frenkel exciton model (FEM) to obtain optical and excitation energy transfer properties of complex molecular systems from the molecular structure. The combination of QC and MD methods with FEM provides a powerful tool to study and explain molecular level processes, which are out of reach of the standard FEM parametrization. We use these methods to study and explain molecular mechanism of excitation energy transfer in rylene dyads, especially to explain observed fast excitation energy transfer in dyad with orthogonal arrangement of transition dipoles, where standard approach predicts no excitation energy transfer. On a fundamental level, we relate FEM to configuration interaction method of QC and propose extension of FEM, which accounts for interaction between excitonic manifolds. We investigate effects of this interaction on the optical properties. Inspired by the core features of FEM, we propose new concept of artificial light harvesting antenna based on fluorographene, with design principles inspired by natural light harvesting complexes. We use structure based methods to investigate its excitation transfer properties. We also introduce a new general method for treating...
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Selforganization and optical properties of small molecular aggregates
Sláma, Vladislav ; Mančal, Tomáš (advisor) ; Chvosta, Petr (referee)
The work deals with the description of carotenoid aggregation in water solutions. The main interactions which are involved in aggregation were analyzed and an efficient way of description of carotenoid aggregation, which leads to a speed up the computation, has been introduced. In addition, two different methods for calculation probability distribution of catotenoids configurations in solutions with variable water concentration were elaborated, and their advantages and disadvantages were discussed. Absorption spectra were calculated from these distributions, and they were compared with the experimental results. The influence of water on formation of different types of aggregates, and its impact on the shape of absorption spectra was also discussed. Results of this study will be used as a base of other, more accurate, description of carotenoids aggregation, which will include other weaker interactions between carotenoids.
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Intensity Normalization of Raman Spectra by Means of Various Internal Standards
Sláma, Vladislav ; Mojzeš, Peter (advisor) ; Procházka, Marek (referee)
The work deals with the testing of selected inorganic anions as internal standards for intensity normalization of Raman spectra. Using the concentration and temperature series of aqueous solutions of PO4 3- , (CH3)2AsO2 - , NO3 - a SO4 2- , impact of the spectral changes of the standard bands for reliability and accuracy of the intensity calibration was studied. Temperature and concentration series of the anion Raman spectra are then used to test normalization by means of the bands of stretching and deformation vibrations of water molecules. In addition, reliability and robustness of the calibration procedures exploiting different spectral parameters present in the Raman spectra of standards was tested. Results of the study reveal possible sources of artifacts and misinterpretations arising from insufficient understanding of the standard behavior due to changes of the physical and chemical parameters, or due to improper calibration procedure applied.
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