Sökning: "trace gas detection"
Visar resultat 1 - 5 av 15 avhandlingar innehållade orden trace gas detection.
1. Mid-infrared photonic devices for on-chip optical gas sensing
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
2. Mid- and near-infrared NICE-OHMS : techniques for ultra-sensitive detection of molecules in gas phase
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. Improved methods for enrichment of organic ultra trace components for analysis by gas chromatography
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
4. Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection
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
5. Laser Remote Sensing for Environmental 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