Das Projekt "Laser Photoakustische Spektroskopie an Gasen" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Quantenelektronik, Laboratorium für Laserspektroskopie und Umweltanalytik durchgeführt. This project is aimed at the development of laser-photoacoustic spectroscopy to trace gas monitoring. Part A involves a home-made mobile CO2 laser photoacoustic system whose potential is further extended by the implementation of several new features such as the use of laser isotopes, photoacoustic Stark cell, multipass cells, etc. The regional field studies focus on VOC, ozone and ammonia monitoring in different environments. In collaboration with FAW Waedenswil the emission of key substances of fruits that are stored under different and varying atmospheres is investigated. Compounds of interest for the fermentation process include ethanol, acetaldehyde, ethyl acetate and others. The second part concerns our high-pressure CO2 laser photoacoustic setup. Thanks to the continuous, rather than only discrete, wavelength tunability and the narrow linewidth of the laser source, this device is particularly suited for the analysis of multicomponent trace gas mixtures. Furthermore, time-resolved monitoring of the generated acoustic pulses and photothermal beam deflection signals is performed. These results yield new insights into molecular relaxation processes and reaction kinetics. Leading Questions: - How versatile are laser spectroscopic detection schemes with respect to atmospheric trace gas monitoring? - Which levels of detection sensitivity and selectivity can be achieved and how do they compare with more conventional techniques? - How suitable are laser techniques for field applications? - How could novel laser developments further improve the potential for environmental sensing?