Computational Calculation of Dissolved Organic Matter Absorption Spectra

Citeable URL: https://scholar.colorado.edu/concern/articles/pn89d8187

Abstract

The absorption spectrum of dissolved organic matter (DOM) is a topic of interest to environmental scientists and engineers as it can be used to assess both the concentration and physicochemical properties of DOM. In this study, the UV–vis spectra for DOM model compounds were calculated using time-dependent density functional theory. Summing these individual spectra, it was possible to re-create the observed exponential shape of the DOM absorption spectra. Additionally, by predicting the effects of sodium borohydride reduction on the model compounds and then calculating the UV–vis absorbance spectra of the reduced compounds, it was also possible to correctly predict the effects of borohydride reduction on DOM absorbance spectra with a relatively larger decrease in absorbance at longer wavelengths. The contribution of charge-transfer (CT) interactions to DOM absorption was also evaluated, and the calculations showed that intra-molecular CT interactions could take place, while inter-molecular CT interactions were proposed to be less likely to contribute.

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