Short-wavelength photon and electron emission in free and deposited nanoparticles by controlled ultrafast laserinduced nanolocalized fields

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The emission of short-wavelength photons and electrons from nanoscopic matter of well-defined size and structure in controlled ultrafast nanolocalized laser fields is investigated. This requires the close collaboration of three research teams from physical chemistry, experimental physics, and theoretical physics. Femtosecond and few-cycle laser pulses are employed to excite isolated nanoparticles as well as arrays of ordered nanoparticles. This allows us to determine the intrinsic properties of nanoparticles, with respect to short wavelength photon emission and electron emission in intense laser and ultrashort laser fields, where the internal composition, size, and shape of the particles are systematically varied. Specifically, we expect focusing effects, if the particle size becomes similar to the wavelength of the exciting photons. Intense fewcycle laser pulses have the specific advantage that metallization of dielectric nanoparticles, nonlinear emission processes, and the emission of short-wavelength photons can be studied, where the interplay between electron emission and formation of short-wavelength radiation is of specific interest. We will also distinguish the coherent and incoherent fractions of the emitted radiation, so that the formation of highharmonics is characterized. Further, control mechanisms of electron and short-wavelength photon emission by using the carrier envelope phase as well as the superposition of the fundamental and the second harmonic of a femtosecond laser pulse are investigated. Theoretical model simulations are of primary importance for assigning the experimental signatures to corresponding microscopic mechanisms and for guiding the experiments by identifying relevant parameter regimes. Based on previous work, a Mie-Monte- Carlo model will be developed in order to study propagation effects in large nanoparticles close to the ionization threshold. Specifically, nanofocusing, evanescent near fields, and local trapping induced by ionization are explored for nanoscopic systems. Furthermore, a novel particle in cell technique will be applied and developed further in order to model the metallization of dielectric nanomaterials, plasma waves, and nonlinearities of dielectric response.