Sökning: "Periodic Array"

Visar resultat 1 - 5 av 7 uppsatser innehållade orden Periodic Array.

  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. LPI waveforms for AESA radar

    Uppsats för yrkesexamina på avancerad nivå, Uppsala universitet/Fasta tillståndets elektronik

    Författare :Andreas Sjöberg; [2020]
    Nyckelord :Radar LPI waveform AESA;

    Sammanfattning : The purpose of low probability of intercept (LPI) radar is, on top of the standard requirements on a radar, to remain undetected by hostile electronic warfare (EW) systems. This can be achieved primarily by reducing the amount of radiated power in any given direction at all times and is done by transmitting longer modulated pulses that can then be compressed digitally in order to retain range resolution. LÄS MER

  4. 3. A Near-Infrared Diffraction Radiation Spectrometer for MHz Repetition Rate Electron Bunch Diagnostics at the European XFEL

    Uppsats för yrkesexamina på avancerad nivå, Uppsala universitet/Tillämpad kärnfysik

    Författare :Simon Fahlström; [2019]
    Nyckelord :European XFEL; XFEL; Free-Electron Laser; FEL; bunch diagnostics; Coherent Diffraction Radiation; Spectrometer;

    Sammanfattning : We have built a spectrometer to investigate the Near-Infrared (NIR) range of this radiation, which is used for bunch diagnostics at the European X-ray Free-Electron Laser. This could give information on the development of microbunching, periodic features in the longitudinal charge profile of the bunches which have a negative impact on the operation of the facility. LÄS MER

  5. 4. Fabrication and Optimization of a Nanoplasmonic Chip for Diagnostics

    Uppsats för yrkesexamina på avancerad nivå, Umeå universitet/Institutionen för fysik

    Författare :Jonas Segervald; [2019]
    Nyckelord :AFM; NIL; SPR; SERS; nanohole; nanohole array; nanoimprint lithography; physical vapor deposition; plasma treatment; plasmonic; plasmons; surface plasmon resonance; localized surface plasmon resonance; metal enhanced fluoresence; surface enhanced raman spectroscopy; transmittance; nanoplasmonic; signal enhancement;

    Sammanfattning : To increase the survival rate from infectious- and noncommunicable diseases, reliable diagnostic during the preliminary stages of a disease onset is of vital importance. This is not trivial to achieve, a highly sensitive and selective detection system is needed for measuring the low concentrations of biomarkers available. LÄS MER

  7. 5. Absorption of light through isolated and coupled resonances in horizontal InP nanowire arrays

    Master-uppsats, Lunds universitet/Fasta tillståndets fysik; Lunds universitet/Fysiska institutionen

    Författare :Ali Hosseinnia; [2015]
    Nyckelord :Coupling; Optical resonances; Horizontal nanowires; Periodic Array; Indium Phosphide; Finite Element Method; Scattering Matrix Method; Eigen function method; Mie Theory; Scattering; Absorption; Nano-Optics; Nanowire; Physics and Astronomy;

    Sammanfattning : We have studied the interaction of light with two types of closely related nanostructures: a single horizontal InP nanowire and an infinite periodic array of such nanowires. The study has been done theoretically by calculating the absorption cross section of the nanowires via a semi analytical method, the Mie theory, and two numerical methods, the scattering matrix method (SMM) and the finite element method (FEM) to perform electromagnetic modeling. LÄS MER