| Salt solution plays an important role in daily life,human health,environmental protection and industrial production.The interaction between salt ions and ice water molecules is closely related to the fact that excessive salt intake tends to raise blood pressure,and that snow and ice sprinkling salt on roads can improve traffic conditions.Hydrogen bond is the basic structure and energy unit of ice water molecules.Salt ions acting on surrounding water molecules induce hydrogen bond network structure to change to show different physical properties.This paper from the O:H—O hydrogen bond cooperative relaxation theory,combined with Raman spectrum test and Lagrangian mechanics,represented by halide solution to explore interaction evolution between solute and solvent caused by the types of anion and cation and concentration and hydrogen bonds relaxation in ion induced hydration shells and the regularity of the evolution of the short range interaction to clear the general rule to ion injection of hydrogen bond network structure and potential field modulation.The main research results of this paper are summarized as follows:(1)Based on the temperature-density dependence,the O:H—O hydrogen bond coupling double section physical property coordination rules were established by using ice water tetrahedron structure,and the relationships among mass density,segmented bond length and phonon vibration frequency were quantified,so as to realize the purpose of knowing the rest if the one is known and reduce the dependence on experimental data.More importantly,this is an internal collaborative relationship,independent of the form of external excitation,which has universal significance for the O:H—O hydrogen bond network structure.(2)The evolution of asymmetric hydrogen bond short range potential field in NaCl solution with different ion concentration was studied in combination with the synergistic relationship between the physical property parameters of coupled double segments and the BOLS theory.It is found that the ionic electric field induces the rearrangement of dipoles of surrounding water molecules towards or away from the central point charge,forming a hydrated shell,and the polarization modulates the hydrogen bond relaxation.When the concentration is lower than 2 M,the hydrating shell of the ion can completely shield the influence of other neighboring ions,presenting an isolated ion state.However,beyond the 2 M concentration,the interaction between ions is d ifficult to be completely shielded,and polarizing water molecular in hydrated shell together.With the increase of ion concentration,the elongate of O:H bond becomes weaker from 39.466 meV to 31.756 meV,and O—O Coulomb repulsion modulating the H—O covalent bond shortens and be stronger from 3.589 eV to 3.873 eV.Beyond the 2 M concentration,the evolution amplitude of length and potential energy decreases obviously.(3)The effects of ion species on the structure and short-range interactions of hydronium shell hydrogen bond network were studied by taking the salt solutions of NaX(X=Cl,Br,I)and YCl(Y=Na,K,Cs) as examples.The results show that with the increase of the halogen ion radius and the decrease of electronegativity,the O:H bond elongation from 1.7076?to 1.7299?,phonon softening and water intermolecular force in NaX solution are weakened.Meanwhile,the H—O covalent bond is shortened from 0.9967? to 0.9902?and hardened,and the force in the water molecule is strengthened,which conforms to the law of I~->Br~->Cl~-and is consistent with the description of Hofmeister sequence.In YCl solution,the influence of cation on hydrogen bond network structure follows the rules of Na~+>K~+>Cs~+.The polarization effect of anions is greater than that of cations,which determines the related properties of salts to some extent. |
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