Water Dynamics and Structure of Highly Concentrated LiCl Solutions Investigated Using Ultrafast Infrared Spectroscopy
Citations Over TimeTop 10% of 2022 papers
Abstract
In highly concentrated salt solutions, the water hydrogen bond (H-bond) network is completely disrupted by the presence of ions. Water is forced to restructure as dictated by the water-ion and ion-ion interactions. Using ultrafast polarization-selective pump-probe (PSPP) spectroscopy measurements of the OD stretch of dilute HOD, we demonstrate that the limited water-water H-bonding present in concentrated lithium chloride solutions (up to four waters per ion pair) is, on average, stronger than that occurring in bulk water. Furthermore, information on the orientational dynamics and the angular restriction of water H-bonded to both water oxygens and chloride anions was obtained through analysis of the frequency-dependent anisotropy decays. It was found that, when the salt concentration increased, the water showed increasing restriction and slowing at frequencies correlated with strong H-bonding. The angular restriction of the water molecules and strengthening of water-water H-bonds are due to the formation of a water-ion network not present in bulk water and dilute salt solutions. The structural evolution of the ionic medium was also observed through spectral diffusion of the OD stretch using 2D IR spectroscopy. Compared to bulk water, there is significant slowing of the biexponential spectral diffusion dynamics. The slowest component of the spectral diffusion (13 ps) is virtually identical to the time for complete reorientation of HOD measured with the PSPP experiments. This result suggests that the slowest component of the spectral diffusion reflects rearrangement of water molecules in the water-ion network.
Related Papers
- → Characterization of Nanoparticles by FTIR and FTIR-Microscopy(2021)61 cited
- → Understanding Why Researchers Should Use Synchrotron-Enhanced FTIR Instead of Traditional FTIR(2008)8 cited
- Application to the Study on FTIR Microspectroscopy in High-performance Fibers(2004)
- → 10 Analysis of the in vivo course of foreign body response to a phycogenic bone substitute using FTIR spectroscopy(2021)
- → Application of Fourier transform infrared-photoacoustic spectroscopy for the characterisation of organic wastes and determination of their usefulness for bioenergy and as soil amendments(2016)