Jump Rotational Mechanism Of Ammonium Ion In Aqueous Solutions

Amino compound is an important component of environmental water,fertilizer and agricultural life of proteins,which plays an important role for the substance in the environment and life cycle processes.Usually,these processes take place in aqueous solution and they are closely related to properties of aqueous solution,such as ammonium ion rotational behavior and the property.Recently,ultrafast spectroscopy found that the rate of rotation of ammonium ions in aqueous solution was much faster than alcohol solution.However,the microscopic mechanism is still not clear.In this paper,the molecular simulation methods and extended jump rotation model were used.The structure,dynamics and the nature of the molecular mechanism of rotation NH4Cl aqueous have been done a detailed study.Molecular simulation is in good agreement with experimental results,and gives a mechanism for the ammonium ion in aqueous solution jump rotation.Based on the theory of fluid mechanics,since there are several strong hydrogen bonds between ammonium ions and water molecule,which should slow its rotation,but the results are not.Our molecular dynamics simulation results show that the aqueous solution of ammonium ions mainly to rapid,wide-angle jump way,follow the same model(EJM,Extended Jump Model)like water molecules.By the decomposition of the rotation mode and two kinds of microscopic rotational relaxation time of comparison,the relative diffusion of ammonium ions and water molecules hydrogen bond skeleton rotation,jump rotation greater contribution to its rotation rate,and increased with increasing concentration.Compared with the exchange of the water molecules hydrogen bond,the exchange of ammonium ion tends to occur between water molecules non-hydrogen directly connected.