The Structural Characterization Of Solvated Dielectron And Theoretical Explorations Of Their Associated Properties

Solvated electrons,an important electron carriers,are a class of weakly bound electrons formed by the interaction of excess electrons with surrounding solvent molecules and such excess electrons are usually generated by pulsed radiation,multiphoton ionization,or electronic photo-desorption solvents.Due to its special reactivity and strong reducibility,solvated electrons have attracted much attention in the fields of physics,chemistry and biological sciences.In recent years,extensive research on the special forms,equilibrium structures,dynamic behaviors,and spectra of solvated single electrons in different media have been carried out by theoretical and experimental workers.Moreover,many of the outstanding results have laid a solid foundation for further in-depth study of the special properties and interesting behaviors of solvated electronic related systems.In fact,in addition to solvated single electrons,there have been studies reported that solvated dielectrons exist in ionic crystals,frozen water glass,molecular clusters,solids,polar solvents,and other media.It also shows that the spin interaction between related excess electrons controls more important electronic properties and systematic characteristics.Therefore,solvated dielectrons are expected to exhibit more attractive features and potential applications.But so far,relative research on solvated dielectrons faces many challenges due to the complex interactions between related excess electrons in the bulk environment and the influence of surrounding environment,causing the information on the structures,states,reactivity and kinetics of the solvated dielectrons is relatively scarce compared to solvated single electrons and needs to be further studied.In this work,the detailed characterization of the structures,states,special properties and dynamic behaviors of solvated dielectrons in liquid methylamine and ice crystal clathrate hydrates are performed by means of quantum chemical calculations and ab initio molecular dynamics(AIMD)simulations.Moreover,the mechanism of the electron-electron spin coupling interaction in dielectron clathrate hydrates and the effect of the electric field on its magnetic properties are also discussed in detail.The innovations and primary research results are briefly described as follows:(1)The Special Dynamic Behavior of Bistable Solvated Dielectrons in Liquid Methylamine.Investigation of the special properties and dynamic behaviors of solvated dielectrons is the focus of the relevant theoretical work.The effective information obtained by AIMD simulations can be used to guide related experiments and further theoretical work.In general,once the excess electrons injected into solutions,they will undergo a process of "dispersion-(quasi)localization-localization"and eventually reach a steady state and evolve dynamically over time.The stable stateof the solvated dielectrons depends on the nature of the solution itself.For example,the excess dielectrons in the ionic liquid maintain the triplet ground state after localization,but the singlet state is the ground state in the 77 K ice environment.Based on this,this part of the work employs liquid methylamine at 253 K as the medium,discussing the dynamic process of the solvation of related excess electrons in liquid methylamine in detail,as well as their structures,states,properties,and dynamic behaviors after complete solvation.The study found that:(a)the solvated dielectrons in liquid methylamine tend to localize in two separate cavities,similar to the two F center structures;(b)both singlet and triplet solvated dielectrons exhibit as the dynamic bipolarons.What is more,the dynamic evolution of singlet solvated dielectron appears as steady state dynamics,while the triplet one exhibits special dynamic behaviors;(c)different from monostable solvated dielectron in ionic liquid or ice environment,the solvated dielectron in liquid methylamine shows bistable state(singlet-state and triplet-state alternate as the ground state)and exhibits unique spin-coupling dynamic behavior.That is,the dynamic bipolaron frequently converts between ferromagnetic and antiferromagnetic states as time evolves.This part of the work reported the dynamic behavior and spin-crossing phenomenon of bistable solvated dielectron in detail in common liquid methylamines for the first time,which has a guiding role in the subsequent research on related solvated dielectron systems.(2)Dielectron Clathrate Hydrates with Unique Superexchange Spin Couplings.In recent years,the discovery of novel electronic structures such as electronic compounds and electron clathrates has motivated researchers to further explore the novel structures and interesting electronic properties of solvated electrons in different systems.Recently,clathrate hydrates have been highly valued by both theoretical and experimental workers due to their enormous potential for gas storage and potential applications in ice crystal materials.At present,the existence of dielectron clathrate hydrates has been observed in experiments,but the relevant information such as its structure and properties has not been reported.This part of the work mainly demonstrated the novel structure of solvated dielectrons and the special superexchange spin coupling and magnetism of the dielectron clathrate hydrates.In addition,the stability,spin coupling mechanism,and the effect of electron distribution on magnetic properties have also been discussed in detail.The results reveal that:(a)the dielectron clathrate hydrates can be stably present in ice and have distinctive bipolaron characteristic.Due to the different structures of water cages which play role of enclosing electrons,the distribution status of related excess electrons are also different.Either two excess electrons are both internal-localized states,or one excess electron is the internal-localized state,and the other is the hydrogen bond network permeation state;b)Two excess electrons interact with each other by means of electron permeating hydrogen bonding networks,exhibiting significant antiferromagnetic coupling and revealing a novel coupling mechanism-the "electron permeating hydrogen bond network coupling mechanism".Moreover,the coupling strength of this coupling mechanism mainly depends on the distribution state and electron center spacing of two electrons in dielectron clathrate hydrates.These results can provide references for predicting the structures,states and magnetism of the solvated dielectrons in different media.(3)Electric Field Effect of Magnetic Coupling of Dielectron Clathrate Hydrates.Solvated dielectrons have special delocalization and mobility,having a significant effect on the conductivity,related optical properties,and magnetic properties of the systems when disturbed by internal or external factors.Therefore,it is widely applied to electrochemical and material chemistry and other fields.However,up to now,there has been little research on the magnetic properties of the electric field-induced solvated dielectron system.Based on this,this part of the work explores the effects of the applied electric field on the magnetic properties of the dielectron clathrate hydrates.It was found that the solvated electrons under different binding states have different sensitivities to external electric fields.The hydrogen bond network permeating-state solvated electrons are more fluid than the solvated electrons in internal localized state,and a weak electric field is sufficient to cause a significant change in their electron distribution,while the internal localized ones need a stronger electric field.Under the influence of an electric field,electron transfer induces the number of electrons that penetrate into the hydrogen bond network to participate in the spin coupling to increase or decrease,thereby causing the magnetic coupling to strengthen or weaken.Therefore,for different dielectron clathrate hydrates,it is possible to effectively achieve the regulation of magnetic strength and even magnetic conversion by applying electric fields in different intensities or different directions.This part of the work further enriches the information on the states and properties of the solvated dielectron system by examining the influence of the electric field on the magnetic properties of the systems,providing a new idea for the magnetic regulation of solvated dielectron systems.In summary,in this paper,first-principles calculations and AIMD simulations are used to systematically investigate and accurately characterize the structures,states,special properties,and behaviors of solvated dielectrons in liquid methylamine and clathrate hydrates,systematically discussing the unique dynamic behaviors of bistable solvated dielectrons in liquid methylamine,the novel superexchange spin coupling mechanism of dielectron clathrate hydrates,and the magnetism changes caused by electric field effects.Solvated dielectrons,magnetic materials,and clathrate hydrates are increasingly attracting the attention of scientific researchers.Combining these three species organically and conducting a deep research on the potential properties of these materials will certainly provide an important theoretical basis and reference for the exploration of new ice crystal magnetic materials and the in-depth study of solvated dielectrons.