Impact of Adsorption of Straight Chain Alcohol Molecules on the Optical Properties of Calcite (10.4) Surface.

Calcium carbonate plays a central role in controlling the chemistry of the oceans, biomineralization and oil production, to name a few. In this work, using density functional theory with semiempirical dispersion corrections and simplified TD-DFT using Tamm-Dancoff approximation, we investigated the impact of the adsorption of straight chain alcohol (ethanol and pentanol) molecules on the optical properties of a calcite (10.4) surface. Our results show that ethanol and/or pentanol molecules form a well-ordered monolayer (through their hydroxyl group with carbon chains sticking away in a standing-up position) on the calcite (10.4) surface. Additionally, we found intriguing modulations in the photoabsorption spectra and circular dichroism spectra. In particular, the latter was a unique optical fingerprint for a molecule-adsorbed calcite (10.4) surface. Our findings provide useful insights into the structural and optical features of calcite-based systems at the atomic level.