Dynamic Parameter Studies Of The Valence-Shell Excitations Of Molecular Oxygen

The energy level structures and dynamic parameters of atoms and molecules are the basic contents of atomic and molecular physics,and they can reveal the basic char-acters of atoms and molecules and have important application values in condense matter physics,plasma physics,atmosphere physics and chemistry.Traditionally,the experi-mental methods of electron scattering spectroscopy and optical spectroscopy are used to measure the dynamic parameters of atoms and molecules.In 2009,our group have extended the high energy resolution X-ray scattering method to determine the dynam-ic parameters of atoms and molecules,such as the elastic and inelastic squared form factors.The first Born approximation is satisfied in this new method,and the experi-mental results determined by it can provide a cross-check with the ones measured by the electron scattering method.In this thesis,the inelastic squared form factors for the Herzberg pseudo-continuum(mainly A/3?u transition),Schumann-Runge continuum(mainly B3?u-transition),Longest-Band and Second-Band(mainly E3?u-(v'=0,1)transitions,respectively.)of molecular oxygen are determined by the inelastic x-ray scattering with a high reso-lution of 70 meV.Comparing the present results with the ones of the electron energy loss spectroscopy,it is found that the validity of the first Born approximation depends on the distinct transitions.The present results of the Herzberg pseudo-continuum show a good consistency with the present electron impact results at 1.5 keV and the ones of Wakiya et al.at electron energies from 150-500 eV in q2<3 a.u.,which infer that the first Born approximation is satisfied in this collision energy region in electron scattering process,but the ones of the Xu et al.at 2.5 keV are smaller than the present one.As for the Schumann-Runge continuum,the present results agree well with the intermediate energy electron impact results,for example,the ones of Suzuki et al.,Wakiya et al.,Newll et al.,Lassettre et al.,in q2<0.5 a.u..But only the present electron impact results at 1.5 keV keep consistence with the present X-ray scattering results in the whole momentum transfer region,which indicates that the first Born approximation is satis-fied in this impact energy and the Xu's results may suffer from the pressure effect.The present results of the Longest-Band are also generally higher than most of the electron impact results,except for the present 1.5 keV electron impact results.This phenomenon is reasonable since the satisfaction of the first Born approximation requires high impact energy.Second-Band undergoes a quick decay when the momentum transfer increases in the present results compared with electron impact results,and the limited data are generally lower than electron impact results,which need further study.In order to improve the performance of the electron energy loss spectrometer and prepare for large angle electron elastic scattering experiment in our laboratory,an elec-tron gun in intermediate-high energy region has been built and tested.The electron gun has a simple structure,i.e.,consisting of thermionic cathode,grid electrode,anode electrode,focus electrode and deflection plates.The tuning range of electron energy is wide(1-3 keV)and easy to operate.To obtain the optimal beam condition,the electron optics software SIMION was utilized to simulate the space size and divergence angle of the electron beam at target position.The beam size of 0.95 mm,divergence angle of 0.93°,and beam current of 6.27 ?A of the constructed electron gun was obtained at 27 mm from the exit of electron gun at a beam energy of 1.5 keV,which satisfies the requirements of electron energy loss spectroscopy.