Related Experiment Video
Updated: Jun 15, 2026
06:48
Fluid-cell Raman Spectroscopy for operando Studies of Reaction and Transport Phenomena during Silicate Glass Corrosion
Published on: May 9, 2025
[Confocal Raman study on ZnSO4 droplets in the efflorescence process]
Han-Shuang Xiao1, Liang-Yu Wang, Yun-Hong Zhang
1Institute of Chemical Physics, Beijing Institute of Technology, Beijing 100081, China. 20407114@bit.edu.cn
Guang Pu Xue Yu Guang Pu Fen Xi = Guang Pu
|March 10, 2010
Summary
Zinc sulfate (ZnSO4) droplet structures transform at the molecular level during efflorescence. As relative humidity decreases, free sulfate ions associate with zinc ions, forming complex contact ion pairs (CIPs) that dominate supersaturated droplets.
Area of Science:
- Materials Science
- Spectroscopy
- Physical Chemistry
Context:
- Investigating the structural evolution of zinc sulfate (ZnSO4) droplets on Teflon substrates during efflorescence.
- Utilizing Confocal Raman spectroscopy to probe molecular-level changes.
- Examining the role of relative humidity (RH) in droplet transformation.
Purpose:
- To elucidate the molecular mechanisms of ZnSO4 droplet structural changes during efflorescence.
- To identify and quantify different species formed as RH decreases.
- To correlate spectral changes with hygroscopic behavior.
Summary:
- Confocal Raman spectroscopy revealed blue shifts in the symmetric stretching band of sulfate ions (SO4(2-)) from 981 cm(-1) to 1,008 cm(-1) with decreasing RH.
- These shifts indicate the formation of various contact ion pairs (CIPs) between Zn2+ and SO4(2-) ions, including monodentate, bidentate, and complex multidentate structures.
- Hygroscopic curve analysis showed two transition points, supporting the observed structural transformations, with free hydrated SO4(2-) dominating at high RH, CIPs forming at intermediate RH, and complex CIPs prevalent in supersaturated droplets below 34% RH.
Impact:
- Provides molecular-level insights into the efflorescence process of ZnSO4 droplets.
- Demonstrates the utility of Confocal Raman spectroscopy for studying solution-state transformations.
- Contributes to understanding the behavior of aerosols and salt solutions under varying humidity conditions.
