Molecular Features of Hydration Layers: Insights from Simulation, Microscopy, and Spectroscopy

Abstract

Water molecules are orderly when stacked on a material surface in a liquid or under ambient conditions. Such a hydration layer plays a crucial role in various chemical and biological processes at interfaces. Significant gaps exist however in our understanding of the molecular structure and dynamics of a hydration layer. Atomic force microscopy (AFM) and vibrational sum frequency generation (VSFG) are widely used to probe the molecular stacking and orientation in a hydration layer. We review the molecular features of a hydration layer extracted from AFM and VSFG and how a molecular simulation can give a clear and quantitative interpretation of these experiments.

Interfacial Liquid Water on Graphite, Graphene, and 2D Materials

“…(a) Scheme of a solid–water interface in a vibrational sum-frequency-generation spectroscopy experiment. Reprinted with permission from ref . Copyright 2022 American Chemical Society.…”

Generalised deep-learning workflow for the prediction of hydration layers over surfaces

“…However, no earlier studies, beyond ours, have applied DL to SPM at solid-liquid interfaces [47]. Furthermore, this work is an entirely different workflow approach from the past studies of DL applied to SPM, due to the system-agnostic descriptor, out-ofdistribution detection technique, training data and DL model.…”

Multimodal Nonlinear Vibrational Hyperspectral Imaging

“…lack inversion symmetry) and have been used to study biomaterials such as collagen and celliluse. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] When using SHG and VSFG to study these tissues, its anisotropic chiral organization leads to tissueonly signals, ignoring the bulk surroundings. 32 While both are sensitive to structural arrangement, VSFG has the additional advantage of extracting chemical specific information because it measures molecular vibrational modes.…”