The Influence Of The Molecular Vibration On The Momentum Distribution Of The Core Electrons

The momentum distribution of valence electrons in molecules has always been the focus of experimental and theoretical,but the momentum distribution of core electrons is also of great significance to the study of molecular structure and properties.This paper discusses the Born-Oppenheimer approximation induced symmetry-broken effect（SBEBOA）on the momentum distribution of core electrons.According to the research status of electron momentum profile at present,the electron momentum distribution of molecules of different systems is calculated and analyzed in detail,and the research of the core electron momentum profile is prospected.The first chapter of this paper reviews the development and current situation of electron momentum profile,and shows the achievements and process of electron momentum profile in theory and experiment.The second chapter introduces the basic theory and method of electron momentum spectroscopy,and expounds the theoretical innovation of this paper in detail.Using the Born-Oppenheimer approximation theory,considering the solution of the electron momentum profile of molecules when the vibration states obey the Boltzmann distribution.And related theoretical mechanism of electron momentum distribution affected by the Born-Oppenheimer approximation induced symmetry-broken effect(SBE^BOA)is proposed.In Chapter 3,the electron momentum profile of n-pentane(C₅H₁₂)and its isomers（C（CH₃）₄,（CH₃）₂CHCH₂CH₃）are investigated theoretically.The results show that the electron momentum distribution of core orbitals of molecules with symmetrical geometry can be strongly affected by the adiabatic vibration.But for isopentane（（CH₃）₂CHCH₂CH₃）molecules with asymmetric geometry,the effect of vibration on the core electron momentum distribution only weak due to the antisymmetric characteristics of its molecular structure.Chapter 4 deals with the effects of vibration on the electron momentum profile of a group of spherical symmetry molecules（CH4,CF4,SF6）.Discussing under the Born-Oppenheimer approximation induced symmetry-broken effect(SBE^BOA),the different changes on the core and valence orbitals electron momentum distribution of molecules with the same geometric structure.It is found that vibration has different effects on the core orbitals electron momentum distribution of similar geometric structure molecules.The effect of vibration on the core electron momentum distribution is very weak for methane（CH₄）molecules whose core orbital configuration components are mainly composed of central atoms.While for CF₄ and SF₆ molecules,the core electron momentum distribution is strongly affected by adiabatic vibration.The adiabatic vibration plays a different role in the similar geometric structure molecules,and this theoretical result can explain the experimental electron momentum profile well.Chapter 5 uses the adiabatic approximation theory to calculate the theoretical electron momentum spectroscopy of N₂O molecules.Considering the symmetry-broken effect caused by adiabatic vibration,and compares it with the experimental results and the theoretical calculation results made by predecessors.And the theoretical electron momentum spectroscopy of n-hexane molecules is studied.Finally,the work of this paper is summarized and some prospects for the future study of electron momentum spectroscopy.