Investigation Of The Interaction Between Three Typical Groups And Oh Stretching Vibration Of Water

Water is the most basic substance in nature.The research on the microstructure of liquid water has always been a hot topic.In 2016,Science published 125 most challenging scientific topics,among which the 46th question is:what is the structure of water?Therefore,it is an ancient and profound subject to study the interaction between groups and water molecules.Although the molecular structure of water is simple,the internal hydrogen bond structure of water is complex.There are still disputes among researchers about the determination of hydrogen bond model of interaction between different groups and water OH stretching vibration.In the dissertation,the interaction between different groups and OH stretching vibration is further investigated by combining spontaneous and stimulated Raman spectroscopy under ambient pressure and dynamic high pressure,hence the hydrogen bond structure in binary aqueous solution can be presented from the microscopic perspective.The changes of vibration frequency and hydrogen bond structure in three representative binary aqueous solutions of acetic acid,potassium iodide/potassium iodate and dimethylformamide（DMF）were studied respectively.The different effects of ambient pressure and dynamic high pressure on the hydrogen bond structure in aqueous solution were compared.Study yielded the following results:1.The acetic acid-water binary solution is a classical hydroxyl-carboxyl mixed system.However,the change of hydrogen bond structure with solution concentration and the interaction between the corresponding groups and OH vibration still need to be further investigated.The spontaneous and stimulated Raman scattering（SRS）spectra of the acetic acid-water binary solution were measured to make a further investigation of these details in the dissertation.According to the interaction of acetic acid C=O vibration,H-C-H vibration and water OH vibration,it is concluded that the hydrogen bond structure transformation points are,respectively,at 30%and 80%by the acetic acid volume ratio under the condition of spontaneous Raman spectroscopy.Compared with the conclusion of spontaneous Raman spectra,the hydrogen bond structure transformation points occur to 15%and 25%by the acetic acid volume ratio under the condition of stimulated Raman scattering（SRS）.The phenomenon is attributed to the focusing of intense laser pulse in the aqueous solution in SRS,which induces the generation of GPa-level dynamic high pressure region and excess electrons.Consequently,the local hydrogen bond structure and OH vibration are affected,leading to the hydrogen bond structure transformation points of acetic acid-water solutions being forward.2.The redox process of I^-and IO₃^-in seawater has a certain destructive effect on the ozone layer.It is helpful to promote the development of basic research on seawater/atmospheric iodine chemistry and take different treatment methods for the two ions by investigating the different effects of I^-and IO₃^-ions on OH stretching vibration in water.The Raman spectra of KI and KIO₃ binary solutions under different concentrations were measured to study the effect of two iodine ions on OH vibration in water.After adding I^-and IO₃^-ions into liquid water,it can be inferred that the hydrogen bond strength is weakened based on the frequency shift of OH stretching vibration peak to high wavenumber.The main reason is that the original hydrogen bond in water is destroyed by I^-and IO₃^-ions by forming hydrogen bond with water molecule OH.Compared with IO₃^-,I^-shows greater frequency shift and spectrum broadening,indicating that the hydrogen bond formed by I^-is weaker and the corresponding OH vibration is stronger.What contributes to the phenomenon is that the radius of I^-is smaller.In the SRS spectra,pure water shows a single peak,and the addition of I^-and IO₃^-ions has a more obvious destructive effect on the hydrogen bond in water.3.DMF is one of the simplest amide compounds,the micro mechanism of interaction between different groups in DMF and OH vibration in water still needs further investigation.In the dissertation,the Raman spectra of DMF-water binary solution at different DMF volume ratios were measured.It is clear that the three hydrogen bond structure transformation points of DMF-aqueous solutions are,respectively,at 40%and 80%by analyzing the frequency shift of OH stretching vibration of water and spontaneous Raman peaks of typical groups of C=O,C-H and H-C-H.In the SRS spectra of DMF-water binary solution,it is found that the hydrogen bond transformation points are being forward to 15%and 20%by the DMF volume ratio through the frequency shift trend of C-N vibration of DMF and OH vibration of water.This is mainly due to the effect of shock wave high pressure and excess electrons.Meanwhile,it is found that the hydrogen bond between DMF and water gradually weakens with the increase of DMF volume ratio in the solution,which enhances the OH stretching vibration.In the dissertation,the interaction mechanism between different groups and OH vibration modes of water molecules in three typical binary aqueous solutions was studied under conventional and extreme conditions,respectively.The corresponding hydrogen bond structure changes under spontaneous and stimulated Raman scattering conditions were compared and analyzed.The results obtained will contribute to further exploring the microphysical mechanism of intermolecular interaction in binary aqueous solutions as well as providing a reference for further mechanism researches in related fields.