Raman Spectroscopy Reveals Isotope-specific Hydrogen Bond Kinetics in a Spherical Droplet leading to Preferential Evaporation of D2O in H2O-D2O Mixture
Year: 2026
Type: preprint
Abstract: The evaporation of a spherical droplet having a pure solvent or a mixture of isotopic forms is fundamental to atmospheric physics, and critical for studying interfacial fluid dynamics, and hydrogen-bond kinetics. Understanding the hydrogen/deuterium bonded structural dynamics at molecular level during evaporation of isotopic water mixture (H2O/D2O) is important for understanding non-equilibrium phase transitions. In this work, we investigated real-time evaporation kinetics of spherical water droplets on superhydrophobic surface by time - dependent Raman spectroscopic method. Specifically, the results give an account for the variation of each H - or D-bonded clusters (ranging from fully tetrahedral ice-like structure to free water molecule) with time in the mixture from the time - dependent intensity change of each distinct vibrational stretching band of O-H or O-D. For pure H2O, the O-H peak intensities for all the clusters were decreasing with time, whereas for pure D2O, the ice-like structures vanished quickly with simultaneous increase in the free D2O molecules. In the mixture of H2O-D2O, based on Raman signal of each species, our experimental measurements suggested that the species having O-D or D2O was evaporating faster in comparison to the species having O-H or H2O. The results were also supported by the molecular dynamics simulation, which revealed that the bulk D2O was moving to the surface, and evaporating faster than H2O molecules.
Source: ChemRxiv
Authors: Sujay Paul, Dinesh Sharma, Arun Chattopadhyay
Institution: Indian Institute of Technology Guwahati
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G282800862, G3311227386, G5109427569
OpenAlex ID: W7220711941