Time‐resolved laser spectroscopy for the trace analysis of PAH‐molecules in water and in the ground

Time‐resolved laser‐induced fluorescence spectroscopy is shown to be a promising tool for new applications in the trace analysis of environmental pollutants. Time‐integrated recording of the decay signal intensity is divided into an ‘‘early’’ and a ‘‘late’’ time window with respect to the excitation pulse. The ratio of these two intensities can be used as a very sensitive indicator for the detection of pollutants in different media and can also be used for a quantitative diagnostics. This recording method simplifies the procedure so that it becomes very attractive for practical applications. The detection limit for hydrocarbon molecules is shown to be 0.5 mg/liter in water and 5 mg/kg in soil.