Probing Local Molecular Structure in Solids and Aqueous Solutions by Vibrational Spectroscopy in the CH/CD and OH Stretching Regions
Ke Lin
Professeur associé à l’Université de Xidian , visiteur à l’ISMO
The local structure of molecules, governed by various intra- and intermolecular interactions, plays a crucial role in many chemical and biological systems. Vibrational spectroscopy is highly sensitive to such local structural variations. In the gas phase, molecular structure and intermolecular interactions can be directly characterized by different vibrational spectroscopic techniques. However, in solids and aqueous solutions, the situation becomes much more complex due to dynamic interactions and severe spectral overlap, making precise structural characterization challenging.
In this presentation, I will demonstrate how Raman, IR, and VCD spectroscopy in the CH/CD and OH stretching regions can be employed to probe: (1) conformational structures of organic compounds in solids and aqueous solutions, (2) the local hydration structure of water surrounding ions and organic solutes, and (3) interfacial water structure at solid–aqueous interfaces. To achieve this, we developed a novel alkyl-group deuteration strategy and a ratio spectral analysis method. These approaches allow us to resolve conformational structures in the CH/CD stretching region, identify contact ion pairs of Li⁺ in dilute aqueous solutions, and reveal ice-like water structures induced by nano-rough solid surfaces in the OH stretching region.