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Visar resultat 1 - 5 av 9 uppsatser som matchar ovanstående sökkriterier.

  1. 1. Time-resolved x-ray diffraction study of longitudinal optical phonons in zincblende semiconductors

    Master-uppsats, Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

    Författare :Lassi Linnala; [2022]
    Nyckelord :femtosecond THz radiation; ultrafast x-ray diffraction; pump-probe; longitudinal optical phonons; zincblende semiconductors; anharmonic decay; density functional perturbation theory; Physics and Astronomy;

    Sammanfattning : Anharmonic decay of longitudinal optical (LO) phonons in zincblende semiconductors is not at present well characterized due to the polar and many-body nature of the problem. Femtosecond THz radiation offers a novel route to this study, as the interaction of this radiation is directly with the phonon lattice and these THz excited phonons do not have enough energy to excite electrons over the band gap. LÄS MER

  3. 2. Pulsed Laser Beam Quality Assessment via Phase Retrieval

    Master-uppsats, Lunds universitet/Atomfysik

    Författare :Mattias Ammitzböll; [2021]
    Nyckelord :GSA; phase retrieval; Gerchberg-Saxton; femtosecond; pulsed; laser; beam quality; attosecond; interferometry; Physics and Astronomy;

    Sammanfattning : In the search for a better understanding of the fundamental nature of the atom, the development of femtosecond pulsed laser sources has opened up for many applications, in particular in time-resolved physics. For many of those, like the generation of attosecond pulses through high-order harmonic generation, high intensity is needed and the quality of the beam is a critical factor. LÄS MER

  4. 3. Optimization of Intense Attosecond XUV Pulses

    Magister-uppsats, Umeå universitet/Institutionen för fysik

    Författare :Xiuyu Wu; [2019]
    Nyckelord :;

    Sammanfattning : To observe electron dynamics in molecules and atoms which takes place on the attosecond timescale, single isolated attosecond pulses are required utilized in performing pump–probe experiments. The Light Wave Synthesizer 20 generates intense sub-5 fs pulses with a peak power of 16 TW and a broad spectrum. LÄS MER

  5. 4. Femtosecond Photoemission Electron Microscopy of Indium Arsenide Nanowires

    Kandidat-uppsats, Lunds universitet/Synkrotronljusfysik; Lunds universitet/Fysiska institutionen

    Författare :Björn Johansson; [2018]
    Nyckelord :Indium Arsenide; PEEM; Femtosecond laser; Time-resolved PEEM; InAs; Wurtzite; zinc blende; pump-probe; Photoemission Electron Microscopy; pulsed laser.; Physics and Astronomy;

    Sammanfattning : PhotoEmission Electron Microscopy (PEEM) has proven to be a successful method for examining the electronic characteristics of nanostructures. The experiments relevant for the following report were conducted using a combination of PEEM and a femtosecond pulsed laser to determine the electrical characteristics of Indium Arsenide nanowire of crystal structure varying between wurtzite and zinc blend. LÄS MER

  7. 5. Photoelectron Spectroscopy using high repetition rate attosecond pulses

    Kandidat-uppsats, Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

    Författare :Lisa Rämisch; [2017]
    Nyckelord :Physics and Astronomy;

    Sammanfattning : In attosecond physics, pump-probe experiments have been a promising tool to study the fundamental light-matter interaction process of photoionization. In this context, photoelectron spectroscopy is used to spatially and temporally characterize the ejected photoelecron. LÄS MER