Ultrashort pulsed laser-induced chemistry : methodology, instrumentation, and analysis

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This dissertation explores the science and application of ultrashort pulsed lasers to locally induced chemical reactions having high spatial resolution. Chemical reactions driven in the gas phase by micro- to millimetre-scale plasmas formed when ultrashort pulsed laser ablation is performed in reactive gas atmospheres are studied via scanning electron microscopy, time-resolved optical emission spectroscopy, spatially resolved fast photography, plasma diagnostics, and mass spectrometry. Surface reactions resulting in metal deposition are explored via energy dispersive X-ray spectroscopy, electron backscatter diffraction, transmission electron microscopy, atomic force microscopy, and the use of a complex scientific instrument known as the TripleBeam designed and developed over the course of the project, and described in detail in this dissertation. With wide scientific and industrial potential as both an experimental platform and a nanofabrication tool, the design and development of the TripleBeam instrument was initially motivated by the need to speed industrial processes currently employing focused ion beams. To that end, gas-phase ultrashort pulsed laser-induced chemistry was explored as a means of protecting sensitive components inside the instrument from material removed during in situ laser ablation. For this reason, reactions resulting in the transformation of solids to gas-phase compounds are targeted. However, a demonstration of the technique as a means for the fabrication of novel nanoparticles is also given. Ultrashort pulsed laser-induced surface chemistries were explored with the hope of improving deposition rates and the purity of deposits made via electron and ion beam-induced processes. A previously unreported technique is presented in which electron-beam induced depositions provide templates for laser induced deposition, enabling both higher deposition rates and sub-diffraction limited pattern resolution. With a rich potential application space driven by fundamental physics, ultrashort pulsed laser-induced chemistry can be seen as both an end in itself and as a means for exploring the complex interaction of light and matter. The work detailed in this dissertation produced methodologies, instrumentation, and analysis relevant to both the fundamental physics and the application of ultrashort pulsed-laser induced chemistry.
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