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Visar resultat 1 - 5 av 191 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Mid- and near-infrared NICE-OHMS : techniques for ultra-sensitive detection of molecules in gas phase

    Författare :Thomas Hausmaninger; Ove Axner; Kyle Crabtree; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; spectrometry; NICE-OHMS; trace gas detection; acetylene; methane; isotopologues; near-infrared; mid-infrared; shot-noise; optical parametric oscillator; teknisk fysik med inriktningen mikrosystemteknik; engineering science with specialization in microsystems technology;

    Sammanfattning : Noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is a technique for ultra-sensitive detection of molecular absorption and dispersion. For highest performance, the technique combines cavity enhancement (CE) with frequency modulation (FM); while the former increases the effective interaction length between the light and the analyte by several orders of magnitudes, the latter removes the in-coupling of 1/f noise and makes the signals background free. LÄS MER

  3. 2. Ultrafast spin, lattice, and electron dynamics in thin metallic films : in the terahertz, near-infrared, and extreme ultraviolet regimes

    Författare :Vivek Unikandanunni; Stefano Bonetti; Andreas Rydh; Jurgen Lindner; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Terahertz; near-infrared; extreme ultraviolet; epitaxial cobalt; transient grating; field emission; gold; platinum; electron-phonon coupling; magneto-crystalline anisotropy; nanoscale dynamics; ultrafast spin dynamics; magnetic inertia; nutation; pump-probe; two-temperature model; Fowler-Nordheim tunneling; fysik; Physics;

    Sammanfattning : In this thesis, we studied the ultrafast spin and electron dynamics triggered by electromagnetic radiation belonging to three different regions of the electromagnetic spectrum, namely terahertz, near-infrared and extreme ultraviolet. By performing pump–probe measurements, we explored the role of the lattice in ultrafast spin and electron dynamics in metallic thin films. LÄS MER

  4. 3. Stream monitoring using near-infrared spectroscopy of epilithic material

    Författare :Jan Persson; Ingemar Renberg; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Streams; environmental monitoring; Water Framework Directive; water quality; biological impact; epilithic material; near-infrared spectroscopy; diatoms; Earth sciences; Geovetenskap;

    Sammanfattning : The European Union Water Framework Directive (WFD), with initiatives to manage surface water resources, has increased the need for fast and inexpensive methods for monitoring conditions in streams. The objective of this thesis is to assess the potential of near-infrared spectroscopy (NIRS) of epilithic material to become such method. LÄS MER

  5. 4. Theoretical Modeling and Near-Infrared Spectroscopy Monitoring of Vial Lyophilization

    Författare :Mikael Brülls; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; in-situ; simulation; monitoring; spectral peak area analysis; near-infrared spectroscopy; lyophilization; moisture; sublimation; vial; mathematical model;

    Sammanfattning : The research documented in this thesis was directed towards lyophilization of pharmaceuticals in vials (vial lyophilization) and it was focused on the design and control of this process. Theoretical modeling has considerable potential to guide experimental studies, thereby decreasing development time and improving the possibilities to achieve an optimal and robust process design. LÄS MER

  7. 5. Carved Mountains and Moving Stones : applications of Near Infrared Spectroscopy for Mineral Characterisation in Provenance Studies

    Författare :Claudia Sciuto; Johan Linderholm; Paul Geladi; Rachel Opitz; Umeå universitet; []
    Nyckelord :HUMANIORA; HUMANITIES; Raw materials; mineral characterization; material agency; Near Infrared spectroscopy; hyperspectral imaging; Energy-Dispersive X-ray Fluorescence; multivariate statistics;

    Sammanfattning : The study of stone artefacts is a combination of anthropological archaeology and geology, rooted in analytical techniques for determining the materials’ composition, typological stylistic classification and interpretation of cultural patterns. In this thesis, the archaeology of materials is considered in the context of sites- and landscape transformation, economic history and development of techniques. LÄS MER