Study alters understanding of acid-base chemistry mechanisms

A new study has revealed important details about acid-base chemistry, focusing on how hydronium (H3O⁺) and hydroxide (OH⁻) ions neutralize each other. Researchers found that this process is mainly driven by electron transfer, rather than the expected proton transfer, especially in isolated systems. Using special water ions and advanced imaging techniques, scientists identified two mechanisms for electron transfer that produce hydroxyl radicals (OH). These radicals are significant in atmospheric chemistry and other scientific fields. The study provides new perspectives on basic chemical reactions and explains an unusual finding of high concentrations of OH and hydrogen peroxide at the surfaces of water microdroplets. Prof. Daniel Strasser from Hebrew University led the research, working with Dr. Richard Thomas from Stockholm University and other experts. The findings are published in Nature Chemistry. They challenge traditional beliefs that the neutralization of hydronium and hydroxide ions only produces water. The researchers noted that these electron-transfer methods could explain the spontaneous formation of OH radicals without needing a catalyst or external energy. Prof. Strasser emphasized the broader implications of these insights for atmospheric chemistry, where OH radicals play a crucial role. To conduct the study, the team recorded the outcomes of neutralization reactions at the DESIREE facility in Stockholm. They used a technique that allows for detailed analysis of individual reactions. This research builds on earlier work where they first detected both electron and proton transfer outcomes. The study also highlights the importance of non-adiabatic dynamics in chemical reactions, which are rapid transitions between electronic states. This area remains challenging for theoretical chemistry. Prof. Henning Schmidt from DESIREE expressed hope that the new evidence will help improve theoretical models. Overall, this research opens new paths for exploring chemical reactions, particularly in atmospheric and extreme environments. It may also have significant implications for environmental science and biomedical research.