Sökning: "phonon"

Visar resultat 11 - 15 av 174 avhandlingar innehållade ordet phonon.

1. 11. Electron-Phonon Interactions in Transition Metal Oxides Studied by Resonance Raman Scattering

   Författare :Jakob Andreasson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Franck-Condon; Fr ohlich interaction; higher order scattering; perovskite; transition metal oxide; two-phonon; oxygen breathing mode; Raman spectroscopy;

   Sammanfattning : In this thesis, studies of strong electron-phonon interactions in a number of transition metal oxides are presented. Two different electron-phonon interaction mechanisms are identified; Franck-Condon scattering and infrared active longitudinal optical (IR LO) two-phonon activation. LÄS MER

3. 12. Modeling Vibrational Electron Energy Loss Spectroscopy with the Frequency-Resolved Frozen Phonon Multislice Method

   Författare :Paul Michel Zeiger; Jan Rusz; Rebecca Nicholls; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Electron Energy Loss Spectroscopy; Phonons; Scanning Transmission Electron Microscopy; Frozen Phonon Multislice; Molecular Dynamics; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : Aberration correctors, improved monochromators, and better detectors have enabled exciting research with nanometer- and Ångstrom-scale resolution in the Scanning Transmission Electron Microscope (STEM). However the interaction of high-energy electrons with the many-body system of the sample is quite complex and hinders interpretation of experiments. LÄS MER

4. 13. Thermal Conductivity of Hygroscopic Foams Based on Cellulose Nanomaterials

   Författare :Varvara Apostolopoulou-Kalkavoura; Lennart Bergström; Tatiana Budtova; Stockholms universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; thermal conductivity; cellulose nanomaterials; foams; hygroscopic; super-insulating; phonon scattering; moisture uptake; heat transport; Materials Chemistry; materialkemi;

   Sammanfattning : Biobased super-insulating materials could mitigate climate change by minimizing the use of petroleum-based materials, creating artificial carbon sinks and minimizing the energy needed to maintain pleasant interior conditions. Cellulose nanomaterials (CNM) produced from abundantly available cellulose sources constitute versatile, highly anisotropic raw materials with tunable surface chemistry and high strength. LÄS MER

5. 14. Frequency comb Brillouin microscopy

   Författare :Felipe Ademir Alemán Hérnandez; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Brillouin light scattering; optics; spinwave spectroscopy; phonon spectroscopy; microscopy; Fabry-Perot interferometer; Frequency comb;

   Sammanfattning : Brillouin light scattering (BLS), an almost a century-old technique, has evolved into a powerful and versatile method to study acoustic and magnetic phenomena down to the nanometer size scale. Presently, BLS can be applied in fields as diverse as acoustics, spintronics, geosciences, and biophysics. LÄS MER

7. 15. Thermodynamical and Dynamical Instabilities from Ab initio Electronic-Structure Calculations

   Författare :Kristin Aslaug Persson; KTH; []
   Nyckelord :electronic structures; density functional theory; phonon instabilities; martensitic transformation; phase diagram;

   Sammanfattning : .... LÄS MER