Synchronous excitation fluorimetry

Fluorescence spectrometry not only provides quantitative or semiquantitative data on concentrations, it may also be used to obtain information on the degree of condensation of humic compounds. Although only the fluorophor and the immediately adjacent parts of the molecule are involved, some useful information may be retrieved. Synchronous fluorescence spectrometry has also been used for remote sensing purposes (Vodacek, 1989). 

This approach is based on the observation that higher degrees of condensation cause red shifts in both the excitation and the emission spectra. In synchronous excitation fluorescence spectrometry (SFS) both the excitation and the emission wavelengths are changed simultaneously at a constant wavelength difference. A A2 value of 18 nm has been shown to be most suitable for this purpose (Miano et al., 1988). The resulting spectra do not provide quantitative information, but can be used to distinguish DHS and PHC oL e.g., different ori- 

Using peak deconvolution techniques (Fig. 25-4) it is seen that synchronous spectra of dissolved humic substances exhibit a highly complex structure. In this case the overall spectrum results from a combination of 14 components. 

Duursma, E.K. (1974), in Optical Aspects of Oceanography Jerlov, N.G., Steemann Nielsen, E. (Eds.). London, New York Academic Press, 1974 pp 237-256. 

Kononova, M.M. (1966), Soil Organic Matter. Oxford Pergamon Press, 1966. 

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It may be also useful to scan the excitation and emission monochromators simultaneously (synchronous fluorimetry). Often, this is carried out by scanning the... 

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