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Visar resultat 1 - 5 av 15 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Mid-infrared photonic devices for on-chip optical gas sensing

    Författare :Floria Ottonello Briano; Kristinn B. Gylfason; Delphine Marris-Morini; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; mid-infrared; mid-IR; photonics; silicon photonics; gas sensing; optical sensing; optical gas sensing; spectroscopy; absorption; dispersion; carbon dioxide; CO2; CO2 sensing; trace gas; ethanol sensing; alcohol sensing; waveguide; photonic waveguide; ring resonator; nanowire; nanoheater; emitter; thermal source; bolometer; microbolometer; thermal detector; high frequency; 3 omega method; plasmonic; platinum; Kanthal; silicon-on-insulator; micro-electro-mechanical systems MEMS ; microfabrication; microsystems; microtechnology; nanotechnology; Optik och fotonik; Optics and Photonics; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : Gas detection is crucial in a wide range of fields and applications, such as safety and process control in the industry, atmospheric sciences, and breath diagnostics. Optical gas sensing offers some key advantages, compared to other sensing methods such as electrochemical and semiconductor sensing: high specificity, fast response, and minimal drift. LÄS MER

  3. 2. 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

  4. 3. Improved methods for enrichment of organic ultra trace components for analysis by gas chromatography

    Författare :Adam Kloskowski; KTH; []
    Nyckelord :water analysis; gas analysis; environmental analysis; sorbent trapping; organic traces; SPME; OTT;

    Sammanfattning : This thesis describes some new methods for analysis oforganic trace components from air and water by gaschromatography. The work is particularly focused on thedevelopment of new technologies for analyte enrichment, usingsorbent-based concepts. Short lengths of open tubular columnswere examined for their potential use as denuders. LÄS MER

  5. 4. Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection

    Författare :Conny Danielsson; Peter Haglund; Karin Wiberg; Jean-Marie Dimandja; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Comprehensive two-dimensional gas chromatography; GC × GC; µECD; PCDDs; PCDFs; dioxins; dioxin-like PCBs; Pressurized liquid extraction; PLE; PLE-C; food; feed; fly ash; soil; Environmental chemistry; Miljökemi;

    Sammanfattning : Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), two groups of struc-turally related chlorinated aromatic hydrocarbons, generally referred to as “dioxins” are of great concern due to their extreme toxicity and presence in all compartments of the environment. Since they occur at very low levels, their analysis is complex and challenging, and there is a need for cost-efficient, reliable and rapid analytical alternatives to the expensive methods in-volving use of gas chromatography high-resolution mass spectrometry (GC-HRMS). LÄS MER

  7. 5. Laser Remote Sensing for Environmental Monitoring

    Författare :Zuguang Guan; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; fiber-optic sensor; gas analysis; food-package monitoring; multiple scattering; zero-background measurement; diode laser spectroscopy; ecological study; aerosol; trace pollutant; LIDAR; laser-induced fluorescence; DIAL; methane monitoring;

    Sammanfattning : This thesis studies the techniques of laser remote sensing and their applications in environmental monitoring, as documented in several published papers. The environment where the human being live is degrading with an accelerating speed. LÄS MER