Erforschung der physikalischen Grundlagen von neuen laserdiagnostischen Verfahren zur quantitativen Analyse reaktiver Stroemungen bei hohen Drucken. Teilvorhaben: Grundlagenforschung zum quantitativen stossfreien Nachweis von Minoritaetenspezies durch laserinduzierte 2D-ps-LIF bei hohen Drucken Abschlussbericht

Laser-induced fluorescence spectroscopy (LIFS) is one of the chief techniques for determining minor species concentrations. One of the main difficulties in the quantitative conversion of LIF signal to species concentration at atmospheric or higher pressures is collisional quenching of the excited states. A solution for the quenching problem of LIFS is the direct determination of effective collisional lifetimes by directly measuring the time dependence of the LIF. To get collisional lifetimes at atmospheric and higher pressures, picosecond pulse lasers with fast detection techniques are required. For this reason, a high-power laser light source was built up, that generates tunable ps-pulses in the UV spectral range. The fluorescence was observed with an intensified ps-gated CCD camera. Thus, the method of direct lifetime measurements was extended to pressures up to 10bar. The relative error of the determined lifetime was limited to 10%. Single-pulse spatially resolved collisional lifetime measurements were performed for the first time in an atmospheric pressure flame (relative error #approx#15%). Single-pulse ps-PLIF is a promising tool to measure the collisional quenching in turbulent flames, where the variations of the collisional environment often are very strong. Furthermore, the RET in OH was regarded by determining rate constants directly from temporally resolved fluorescence spectra at p=1 bar. The results of this work confirm the capability of time-resolved LIFS for quantitative OH imaging in combustion processes and spatially resolved lifetime measurements using ps-laser pulses and fast-gated CCD cameras. The single-pulse experiments provide an important contribution for future application of LIF-techniques in turbulent media. (orig.)Available from TIB Hannover: F99B7+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman