Investigation Of The Dynamic Parameters Of N₂、H₂S、CCl₄

The dynamic parameters of atoms and molecules,including the elastic and inelastic scattering cross sections of atoms and molecules with electrons and X-rays,oscillator strengths and integral cross sections,are one of the key research contents of atomic and molecular physics.The dynamic parameters contain the information of the wave functions of the ground and excited states,and the insight into the wave functions is the basis for the study of larger systems and complex physical and chemical processes.Therefore,accurate dynamic parameters of atoms and molecules are conducive to further understanding the structure of matter and chemical phenomena.In addition,since the atomic and molecular dynamics processes extensively exist in nuclear fusion,plasma,interstellar space and chemical reactions,accurate dynamic parameters such as oscillator strength and integral cross section are also important for understanding and modeling these processes.Based on the nonresonant inelastic X-ray scattering spectrometer at the BL15U line station of Shanghai Synchrotron Radiation Facility,the generalized oscillator strengths of the inner shell excitations of N₂ and CO₂ have been measured.In addition,based on the high resolution electron energy loss spectrometer,the dynamics parameters of the valence shell excitations of H₂S and CC14 have been measured.The vibronic effect in the valence shell excitation of CC14 has also been analysed with the Time-dependent density functional theory calculations.Finally,the NEO-CISD（-）method is developed in the framework of nuclear-electron orbit method,and the dynamic parameters and vibronic effect of the valence shell excitation of HF₂^-have been studied by this method.The specific work of this thesis is as follows:1.The non-resonant inelastic X-ray scattering spectrometer at the BL15U station of Shanghai Synchrotron Radiation Facility has been optimized.Based on this spectrometer,the generalized oscillator strengths of 1s→lπg of N₂ and of C1s+2π_u^*of CO₂ were measured.Since the generalized oscillator strengths measured by the nonresonant inelastic X-ray scattering method always meet the first-order Born approximation,the experimental results can be regarded as the high energy limit of the results of the electron scattering method.The present results provide a strict test for previous electron scattering measurements and theoretical calculations.By comparing our result with previous experimental and theoretical ones,we found that the measurement at 3.4keV incident electron energy does not satisfy the first-order Born approximation.For the C1s→ 2π_u^*of CO₂,the previous calculated generalized oscillator strength results are higher than the present results in the large momentum transfer range,which indicates that the accuracy of the wave function still needs to be improved,and further theoretical works are greatly recommended.2.The valance shell excitations of hydrogen sulphide have been studied by the fast electron impact at a collision energy of 1.5 keV and an energy resolution of about 70 meV.By analysing the variations of intensity and shape of the feature in the range of 5.0-7.5 eV at different scattering angles,the excitation energy of 5.85±0.01 eV and the line width of 0.801±0.01 eV of the 3b₂¹A₂ state have been determined.The generalized oscillator strengths of the valance-shell excitations in the energy range of 5.0-9.2 eV of hydrogen sulphide have been determined from the measured spectra.The corresponding optical oscillator strengths have been obtained by extrapolating the generalized oscillator strengths to the limit of zero squared momentum transfer.The integral cross sections have also been systematically determined from the threshold to 5000 eV by the means of the BE-scaling method;3.The valence shell excitations of carbon tetrachloride have been studied by fast electron impact at a collision energy of 1.5 keV and an energy resolution of about 70 meV.The dipole-forbidden transition of a1σ*←2t1 has been clearly observed at large momentum transfers,and its excitation energy of 6.15 eV has been determined.Two new features are also recognized at 10.04 eV and 10.26 eV.The generalized oscillator strength of each excited state of carbon tetrachloride between 5-11.3 eV has been determined from the measured spectra.To describe the vibronic effect,the GOS of a1σ*← 2t1 transition has been calculated by the Time-dependent density functional theory with the vibronic effect considered.The optical oscillator strength of each transition has also been obtained by extrapolating the generalized oscillator strength to the limit of zero squared momentum transfer.The integral cross sections have also been systematically determined from the threshold to 5000 eV by means of the BE-scaling method;4.NEO-CISD（-）method is developed in the framework of nuclear-electron orbit method.Using this method,the optical oscillator strength density spectrum of HF₂^-have been calculated,and obvious vibronic effects can be observed in the calculated spectra.The generalized oscillator strength of Πg state is also calculated by NEO-CISD（-）method and polynomial fitting method.The results of these two method agree well,which indicates that the NEO-CISD（-）method can calculate the dynamic parameters including vibronic effects.This method provides a new way to deal with the vibronic effect in the dynamic parameters of atomic and molecular excited states.