Sökning: "trace gas"

Visar resultat 6 - 10 av 71 avhandlingar innehållade orden trace gas.

  1. 6. 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. 7. 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

  4. 8. Transport and chemical processing of trace gases in deep convective clouds

    Författare :Roman Bardakov; Annica M. L. Ekman; Mary C. Barth; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; gas transport; atmospheric chemistry; convective cloud; box model; new particle formation; atmosfärvetenskap och oceanografi; Atmospheric Sciences and Oceanography;

    Sammanfattning : Deep convective clouds can efficiently transport trace gases from the planetary boundary layer to the upper troposphere. Once there, some gases will contribute to new particle formation and growth, eventually producing aerosols that are large enough to influence cloud properties, the radiative budget of the Earth, and climate. LÄS MER

  5. 9. Isotope analysis of trace and ultra-trace elements in environmental matrices

    Författare :Nicola Pallavicini; Per Andersson; Luleå tekniska universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied Geology; Tillämpad geologi;

    Sammanfattning : High precision isotope ratio measurements have found increasing application in various branches of science, from classical isotope geochronology to complex multi-tracer experiments in environmental studies. Progress in analytical technologies in recent years has allowed higher quality data to be obtained through mass spectrometry. LÄS MER

  7. 10. New concepts and techniques for quantification and trace analysis by gas chromatography

    Författare :Johan Pettersson; Johan Roerrade; Jan Åke Jönsson; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemistry; quantitative accuracy; calibration; extenal standards; valume contraction; molar excess volume; Kemi; Chemistry; Kemi;

    Sammanfattning : In the first part of this thesis, strategies for avoiding systematic errors when quantifying the main components in mixtures of solvents has been developed (paper I). It is shown that variations in density caused by variations in sample composition and/or volume contraction need to be taken into account. In this way, quantification can be improved. LÄS MER