CITE.CC academic search helps you expand the influence of your papers.
Abstract
In liquid water the transfer of an excess proton between two water molecules occurs through the Zundel cation, H2O···H+···OH2. The proton-transfer mode is the asymmetric stretch of the central O···H+···O moiety, but there is no consensus on its identification in the infrared spectra of acidic aqueous solutions. Also, in experiments with protonated gas-phase water clusters, its position shifts with cluster size, which makes its relationship with solution spectra unclear. Here we introduce a ‘clusters-in-liquid’ approach for calculating the infrared spectrum from any set of charges, even single protons. We apply this procedure to multistate empirical valence-bond trajectories of protonated liquid water and to ab initio molecular dynamics of the protonated water dimer and hexamer in the gas phase. The calculated proton-transfer mode is manifested in both systems as a peak near 1,740 cm−1, in quantitative agreement with a band of similar frequency in the experimental infrared spectrum of protonated water clusters. The infrared spectra of gas-phase protonated water clusters and protonated liquid water have been calculated from molecular simulations using a ‘clusters-in-liquid’ approach, which is restricted to a selected set of charged atoms. The infrared absorption due to the central proton in the H2O···H+···OH2 moiety is found near 1,740 cm−1. Cite this article
Kulig, W., Agmon, N. A ‘clusters-in-liquid’ method for calculating infrared spectra identifies the proton-transfer mode in acidic aqueous solutions. Nature Chem 5, 29–35 (2013). https://doi.org/10.1038/nchem.1503 