2000•Environmental Science & TechnologyRequires access
Fluorescence of Humic Acids (HA) and Pyrene-HA Complexes at Ultralow Temperature
Michael U. Kumke, Fritz Hartmann Frimmel, Freek Ariese, Cees Gooijer
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Abstract
The interaction of pyrene with humic acids of different origins was investigated using fluorescence line narrowing (FLN) spectroscopy at 10 K. FLN spectroscopy can be used to obtain vibrationally resolved fluorescence spectra from samples that under ordinary conditions suffer from extensive spectral broadening. Due to the presence of humic acid the site distribution and the relative intensities of the ground-state vibrations in the fluorescence spectrum (Ham-effect) of pyrene were changed. Both effects were related to the altered microenvironment of pyrene in the presence of humic acid. On the other hand, for humic acids no fluorescence line narrowing effect was observed indicating the occurrence of intra- and intermolecular processes.