Sökning: "spectral diffusion"

Visar resultat 1 - 5 av 53 avhandlingar innehållade orden spectral diffusion.

1. 1. Heterogeneous Materials - Diffusion, Laplace Spectrum, and Nuclear Magnetic Resonance

   Författare :Matias Nordin; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; eigenfunctions; eigenvalues; propagator; diffusion; Laplace operator; Nuclear Magnetic Resonance;

   Sammanfattning : In this thesis diffusion in heterogeneous materials is studied using spectral analysisof the Laplace operator. Relations to the effective diffusion constant and therelaxation rate of the time-dependent diffusion coefficient for porous systems arederived from the Laplace operator’s spectrum. LÄS MER

3. 2. Measuring Material Properties through Gradient Based NMR: Diffusion and Imaging

   Författare :Ingrid Åslund; Fysikalisk kemi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; intracellular diffusion; homogeneous length-scale; material properties; emulsions; yeast suspensions; lamellar phase; NMR; self-diffusion; membrane permeability and bending rigidity;

   Sammanfattning : In this work new methods based Nuclear Magnetic Resonance (NMR) have been developed to measure different kinds of structural properties in soft materials. The advantage of using NMR as a technique to measure material properties is that it is non-destructive, which makes it possible to measure on the actual piece of material that will be used for the application. LÄS MER

4. 3. Nano-segregated soft materials observed by NMR spectroscopy

   Författare :Anton Frise; István Furó; Monika Schönhoff; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; nuclear magnetic resonance; soft matter; colloidal dispersion; carbon nanotubes; colloidal silica; adsorption; liquid crystals; ionic liquids; diffusion; Physical chemistry; Fysikalisk kemi;

   Sammanfattning : This thesis is about using nuclear magnetic resonance (NMR) spectroscopy for studying soft materials. Soft materials may be encountered everyday by most readers of this thesis, for example when taking a shower or watching TV. The usefulness of these materials originates from them being soft yet, at the same time, having some kind of a structure. LÄS MER

5. 4. Single-­molecule spectroscopy of π-­conjugated polymers

   Författare :Oleg Mirzov; Kemisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; fluorescence lifetime; low temperature; spectral diffusion; blinking; MEH-PPV; Single-molecule spectroscopy; π-conjugated polymers; 2D polarization; Monte Carlo; energy transfer;

   Sammanfattning : When applied to condensed-matter samples of large organic molecules, optical spectroscopy faces the problem of inhomogeneous broadening caused by the diversity of environments and conformations that sample molecules are subjected to. This severely limits the information that can be extracted from optical spectra. LÄS MER

7. 5. Some Markov Processes in Finance and Kinetics : Markov Processes

   Författare :Mattias Sunden; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; CGMY process; Collision kernel; Direct simulation Monte Carlo; Diffusion approximation; Extreme value theory; Feller process; Generalized hyperbolic process; Generalized $z$-process; Infinitesimal generator; Laplace-Beltrami operator; L evy Processes; Long-tailed distribution; Kac equation; Kac model; Markov process; Semigroup; Semi-heavy tailed distirbution; Spectral gap; Subexponential distibrution; Superexponential distribution; Tauberian theorem; Thermostat.; Diffusion approximation;

   Sammanfattning : This thesis consists of four papers. The first two papers treat extremes for L\'evy processes, while papers three and four treat the Kac model with unbounded collision kernel. LÄS MER