Search for dissertations about: "photoexcitation"

Showing result 1 - 5 of 17 swedish dissertations containing the word photoexcitation.

2. 1. Quantum Chemical Modeling of Dye-Sensitized Titanium Dioxide : Ruthenium Polypyridyl and Perylene Dyes, TiO2 Nanoparticles, and Their Interfaces

   Author : Maria J. Lundqvist; Sten Lunell; Petter Persson; Lars Ojamäe; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Quantum chemistry; density functional theory; chromophore; nanocrystal; interface; photoexcitation; triplet state; surface electron transfer; electronic coupling strength; Kvantkemi; Quantum chemistry; Kvantkemi;

   Abstract : Quantum chemical calculations have been used to model dye-sensitized nanostructured titanium dioxide systems that can be used in solar cells for solar energy to electricity conversion. Structural, electronic and spectral properties of isolated dyes and both bare and dye-sensitized TiO2 have been calculated with density functional theory, providing detailed information about both the separate parts and the dye-TiO2 interface. READ MORE

4. 2. Microscopic Theory of Charge Complexes in Atomically-Thin Materials

   Author : Raul Perea Causin; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; phonons; trions; dynamics; propa- gation; excitons; many-body physics; dissociation; photoluminescence; 2D materials;

   Abstract : Atomically-thin materials have emerged as the most promising two-dimensional platform for future optoelectronic applications and for the study of quantum many-body physics. In particular, transition metal dichalcogenides (TMDs) exhibit strong Coulomb interaction, resulting in the formation of tightly-bound electron-hole complexes that dominate optics, dynamics, and transport. READ MORE

5. 3. A theoretical perspective on photoinduced reactions - based on quantum chemical models and non-adiabatic molecular dynamics

   Author : Sambit Das; Michael Odelius; Mårten Ahlquist; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Non-adiabatic dynamics; Molecular dynamics; Surface hopping; TDDFT; X-ray absorption spectroscopy; kemisk fysik; Chemical Physics;

   Abstract : The broad range of applications for photochemical reactions is the result of light-matter interaction at the electronic level. The diverse application of photochemistry in various fields, including photovoltaic materials, molecular switches, and biological systems are due to electronic and structural transformations induced by photoexcitation as well as molecular alteration due to electron and charge transfer. READ MORE

6. 4. Time-Resolved Photoemission Electron Microscopy: Development and Applications

   Author : Lukas Wittenbecher; NanoLund: Centre for Nanoscience; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; PEEM; time-resolved PEEM; ultrafast optics; pulse shaping; plasmonics; semiconductor nanowires; hot electrons; ultrafast microscopy; charge carrier relaxation;

   Abstract : Time-resolved photoemission electron microscopy (TR-PEEM) belongs to a class of experimental techniquescombining the spatial resolution of electron-based microscopy with the time resolution of ultrafast opticalspectroscopy. This combination provides insight into fundamental processes on the nanometer spatial andfemto/picosecond time scale, such as charge carrier transport in semiconductors or collective excitations ofconduction band electrons at metal surfaces. READ MORE

7. 5. Photo-induced Structural Dynamics in Transition Metal Dichalcogenides

   Author : Shaozheng Ji; Jonas Weissenrieder; James Gardner; Oscar Tjernberg; Fabrizio Carbone; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; ultrafast electron microscope; coherent shear phonon; photo-induced phase transition; 1T-TaSe2; Td-WTe2; charge density wave; ultrasnabbt elektronmikroskop; koherent skjuvphonon; fotoinducerad fasövergång; 1T-TaSe2; Td-WTe2; laddningsdensitetsvåg; Material and Nano Physics; Material- och nanofysik;

   Abstract : Ultrafast electron microscope (UEM), a combination of transmission electron microscopy and laser-based pump-probe techniques, facilitates ultrafast imaging, diffraction, and electron-spectroscopy with high spatial resolution. The unique advantages of UEM enable local ultrafast dynamic studies in materials, nano-system, and biology. READ MORE