FLUORESCENCE STUDIES OF COMPLEX COAL LIQUID SAMPLES USING THE LIFETIME SYNCHRONOUS SPECTRUM (LISS)

An analysis of coal liquids is demonstrated in the first application o f the lifetime synchronous spectrum (LiSS) to the characterization of complex samples. The measurement of wavelength-resolved fluorescence l ifetimes in the LiSS is shown to enhance the fingerprinting of coal li quids relative to conventional synchronous luminescence spectroscopy. The concentration independence of fluorescence lifetimes of individual compounds provides unique information about the composition of the co al liquids and the sources of their spectral features, indicating simi larities among different samples and leading to the identification of regions in the synchronous spectra that are best for discriminating am ong the samples. The LiSSes also provided information about the nature of the processes responsible for spectral red shifts that occurred wi th increasing concentration of coal liquid.