Study of microwave non-thermal effects on hydrogen bonding in water by Raman spectroscopy

Authors: Han G, Liu F, Zhang T, Xu W, Zhang Y, Wu N, Ouyang S

Year: 2022 Sep 22

Category: Chemistry

Journal: Spectrochim Acta A Mol Biomol Spectrosc

DOI: 10.1016/j.saa.2022.121877

URL: https://pubmed.ncbi.nlm.nih.gov/36174402/

Abstract

Overview

Microwave chemistry has been crucial in organic synthesis, yet the presence of non-thermal effects caused by microwaves remains debatable. This study investigates these effects using Raman spectroscopy to analyze the behavior of water under different heating methods.

Findings

  • The Raman spectra of pure water were compared under oil bath and microwave heating. It was found that microwaves cause a significant shift in the OH stretching band Raman shift due to temperature changes and the deformation of hydrogen bonds.
  • Microwave heating disrupts the hydrogen bond network more severely than traditional oil bath heating, transforming the hydrogen-bonding structures from fully bonded networks into partially bonded and free H2O structures more rapidly.
  • The transformation under microwave influence results in chain-like structures from previously stable tetrahedral configurations, indicating a persistent effect of microwaves on hydrogen bonding for over an hour.

Conclusion

This research confirms the microwave non-thermal effects on hydrogen bonding, providing an experimental basis for understanding the impact of microwave heating in molecular chemistry and potentially its implications on health and safety.

microwave chemistry Raman spectroscopy hydrogen bonding non-thermal effects organic synthesis
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