Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"organic crystals"”.
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Studies of Thermal Transformations in Organic Crystals
… frontal migration in the long direction of the crystals. An investigation of the crystal structures of both forms was completed. Crystals of 1A were monoclinic, space group P2(,1/c) and z = 4. a = 6.810(2), b = 11.125(4), c = 17.178(5) (ANGSTROM), (beta) = 109.38(2)(DEGREES). Crystals of 1B were …
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The study of organic crystals by atomic force microscopy
Organic crystals are found in everyday goods such as foods, drugs, dyes, and agricultural products. To better understand the solid-state behaviour of organic crystals, the study of their surfaces is crucial, as several reactions occur at the interface between the crystal surface and its immediate …
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A computational investigation of nucleation processes in organic crystals
… techniques to elucidate nucleation mechanisms in organic crystals. Specifically, the newly developed methods of aimless shooting and likelihood maximization are applied for the first time to study nucleation processes in complex and technically relevant systems. The first portion of the thesis …
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Two-photon absorption and nonlinear polariton effects in organic crystals
… (SHG) have been studied in phenanthrene crystals at low temperatures (2 to 6K) in order to investigate mechanisms of two-photon absorption (TPA), the relationship between TPE and SHG, and polariton effects. The transition studied is of special interest because it is both one- and …
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Triplet-Exciton Pairs in Organic Crystals: Optical Properties of TIPS-tetracene
Contains fulltext : 331368.pdf (Publisher’s version ) (Open Access)
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Heat transport in Thermoelectric materials: from Layered systems to organic crystals
… to the class of TMD (TaS2 and MoS2) and organic molecular crystals (BTBT, DNTT), using both ab-initio techniques and MD simulations. TMDs have high electrical properties, making them ideal for TE applications, but showed large k that decreases their possible use as TEG. Thus, after a …
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Directing the Assembly of Multicomponent Organic Crystals. Synthesis, characterisation and structural analysis of multicomponent organic systems formed from dynamic processes.
… In recent times, the assembly of multicomponent organic systems has achieved considerable impetus with the widespread interest in co-crystal systems. However, cogent assembly (or engineering) of multicomponent materials is still in its infancy. Considerable advances in crystal design have been …
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Structural studies of organic crystals of pharmaceutical relevance. Correlation of crystal structure analysis with recognised non-bonded structural motifs in the organic solid state
Pharmaceutical solids tend to exist in different physical forms termed as polymorphs. Issues about pharmaceutical systems are mainly concerned with the active ingredient's physico-chemical stability and bioavailability. The main aim of this study is to investigate the non-bonded interactions in …
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A computational analysis of the vibrational absorption of molecular solids in the teraherz range
… for the study of molecular solids, in particular organic crystals of pharmaceutical interest. Most of the work has been performed using two computational packages aimed at the interpretation of the spectra, one based on molecular forcefields (DMACRYS), the other on solid state density functional …
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Computer-aided rational solvent selection for pharmaceutical crystallization
… of solvent on the polymorphism and morphology of organic crystals using molecular modeling techniques. The two most important contributions of this thesis are listed below. 1. We studied the self-assembly of solute molecules in solutions prior to nucleation for two polymorphic systems, tetrolic …
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Terahertz-field-induced nonlinearity in phonons, electrons and spins
… pulses covering several spectral ranges using inorganic and organic crystals and developed linear and nonlinear THz spectroscopy techniques to interrogate light-matter interactions based on different observables and/or symmetry criteria.
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Design and construction of instruments for exciton diffusion characterization and for patterning of thin films
… the instruments explore two main aspects of organic optoelectronic devices. One instrument characterizes exciton diffusion and the other patterns organic thin films. Exciton diffusion characteristics are important to study in organic materials because excitons mediate the transport of energy. …
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Nonlinear Luminescence Quenching in Eu2O3
… has been documented in numerous systems such as organic crystals, rare earth insulators, laser materials, semiconductors, and phosphors. In each of these systems nonlinear luminescence quenching occurs under conditions of high excitation density from interactions between excited centers, the …
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Quantum dynamics in condensed phases : charge carrier mobility, decoherence, and excitation energy transfer
… First, we study charge-carrier mobilities in organic molecular crystals, and develop a microscopic theory that describes both the coherent band-like and incoherent hopping transport observed in organic crystals. We investigate the structures of polaron states using a variational scheme, and …
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An Assessment Of Forcite Approaches In Predictiing Young’s Modulus From Crystal Structure
… systematically evaluated using a large set of crystals. The goal of the current study was to evaluate accuracy of predicted Young’s modulus (E) using the Forcite module in commercial software, Material Studio. The predicted E values of 50 organic crystals were compared to experimental values …
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Polymorphism control and the formation of organic molecular nanocrystals
The formation of organic molecular nanocrystals is a topic of great interest in the pharmaceutical industry because of the potential increase in dissolution rate and solubility of organic crystals below 1 ptm and their potential use in drug products. Previous investigators have developed various …
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CxNy-materials from supramolecular precursors for “All-Carbon” composite materials
… lattice are substituted by nitrogen, to the organic semiconductor graphitic carbon nitride (g-C₃N₄), with a structure based on tri-s-triazine units. In general, composites can reveal outstanding catalytic properties due to synergistic behavior, e.g. the formation of electronic …
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The effects of strain on the electronic and optical properties of rubrene single crystals
Organic semiconductors are an emerging class of materials which show great potential for a wide range of applications yet, despite intense efforts to understand the physics at play in these systems, there remain many open questions. One leading theory for charge transport in these materials is that …
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On new allotropes and nanostructures of carbon nitrides
… into the well-defined morphology of these organic crystals, which are not based on 0D or 1D constituents like known molecular or short-chain polymeric crystals but on the packing motif of extended 2D frameworks. The proposed crystal structure of this g-C3N4 species was derived in analogy to …