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Abstract

Volcanic gases are part of the fundamental geochemical cycles on Earth. They provide information on the planet’s interior and influence the climate and the oxidation state of the atmosphere. However, there remain severe inconsistencies between field observations and models within the field of volcanic gas analysis. This cumulative thesis aims to improve the understanding of volcanic degassing processes by combining three different but related approaches: (1) A model for the chemical kinetics within the early turbulent mixing process of hot magmatic gases with atmospheric air is developed. It questions conventional approaches that assume thermodynamic equilibrium during the gas emission phase and, hence, has severe implications for current interpretations of volcanic gas measurements. (2) A high-resolution spectrograph is conceptualised and developed. The resolving power of ca. 100000 exceeds that of conventional field-deployable instruments by more than two orders of magnitude. Its high light throughput and mobility enables a range of new volcanic measurements, such as the quantification of the hydroxyl radical, which is an important intermediate species in hot volcanic gases. (3) A novel imaging technique for volcanic trace gases is developed. It significantly enhances the accuracy of volcanic volatile flux quantification and shows great potential for spatially resolving the still poorly constrained halogen conversion processes within volcanic plumes. Prototypes of both instrument developments demonstrate their anticipated performance in field measurements. The techniques introduced in this thesis also exhibit extensive potential for further atmospheric remote sensing applications including improved measurements of greenhouse gases, air pollutants, atmospheric oxidants, or plant fluorescence.