Sökning: "Femtosecond laser pulses"
Visar resultat 1 - 5 av 56 avhandlingar innehållade orden Femtosecond laser pulses.
1. Nonlinear optical techniques for ultrafast laser diagnostics : Development of femtosecond LIF, LIGS, CARS and backward lasing
Sammanfattning : The thesis work concerns development and application of four versatile nonlinear optical techniques, based on exploiting ultrashort laser pulses, for diagnostic purposes in gases and flames. The four techniques, all laser-based, are two-photon laser-induced fluorescence (TPLIF), hybrid femtosecond/nanosecond (fs/ns) rotational coherent anti-Stokes Raman scattering (fs/ns RCARS), fs-laser-induced grating spectroscopy (fs-LIGS), and backward lasing. LÄS MER
2. Generation of Ultrashort Pulses – From Femtoseconds to Attoseconds
Sammanfattning : Electronic dynamics takes place on the attosecond timescale and can thus only be studied using a tool with attosecond temporal resolution. High harmonic generation (HHG) provides coherent attosecond pulses in the extreme ultraviolet spectral region. LÄS MER
3. Ionization of large molecules with short laser pulses
Sammanfattning : The decay dynamics of fullerenes and polyaromatic hydrocarbons (PAH) after femtosecond-laser excitation have been studied experimentally by electron momentum mapping and mass spectrometry. The electron spectra of fullerenes and large PAH-molecules were found to be exponentially decreasing with energy without any distinct peaks outside the photon energy. LÄS MER
4. Controlled Trapping in Laser Wakefield Accelerators
Sammanfattning : Experimental studies of laser-driven acceleration of charged particles, in particular electrons and protons, are described in this dissertation. Tightly focused femtosecond laser pulses with intensities exceeding 1018 W/cm2 were used to accelerate charged particles to high energies over distances of a few millimeters. LÄS MER
5. Ultra-intense laser-plasma interaction for applied and fundamental physics
Sammanfattning : Rapid progress in ultra-intense laser technology has resulted in intensity levels surpassing 1022 W/cm2, reaching the highest possible density of electromagnetic energy amongst all controlled sources available in the laboratory. During recent decades, fast growth in available intensity has stimulated numerous studies based on the use of high intensity lasers as a unique tool for the initiation of nonlinear behavior in various basic systems: first molecules and atoms, then plasma resulting from the ionization of gases and solids, and, finally, pure vacuum. LÄS MER
