Relativistic Theoretical Study On Electron Impact Excitation Processes Of Zinc Atom

Electron-atom?ion?impact excitation?EIE?and de-excitation radiation are basic dynamic processes existing in various astrophysics,laboratories and fusion plasmas.Accuracy cross-sections,rate coefficients,radiative wavelength and probability are important atomic parameters for simulating and diagnosing plasma spectra.In recently,the electron impact excitation of Zn atoms has attracted extensive attentions.As an important substitute for mercury in fluorescent lamps,Zn has very important applications in industrial production.It has complex shell structure with Zn,the study of the electron impact excitation for Zn atoms is great significance to reveal the complex electron correlation effect and relativistic effect.In this thesis,the calculation program REIE06 which is based on the full relativistic distorted wave theory method are used to systematically study the electron-impact excitation of Zn atoms.Firstly,the GRASP2K program which is based on the Multi-Configuration Dirac-Fock?MCDF?theory method was used to calculate the energy levels and wave functions for target Zn atom.In order to improve the accuracy of target state calculation,three electronic correlation models,namely,single configuration approximation?Model A?,Valence-Valence electron correlation?Model B?and Valence-Valence+Core-Valence electron correlation?Model C?,are constructed to gradually expand the relativistic configuration basis.The results show Valence-Valence electron correlation has an important influence on the accurate of calculation target energy levels.The difference between the energy level of Model B and Model A is close to 14.6%,while the difference between the energy level of Model C and Model A is close to 15.1%.The results obtained in Model C are compared with the NIST experimental data,and the deviation is less than 0.8%.Furthermore,a systematically calculation are performed to obtain the total and differential cross sections for spin polarized electron-impact excitation of Zn atom from the ground state 4s^{2 1}S₀to the excited state 4s4p ¹P₁with incident electron energy within 10-80e V.At the same time,Stokes parameters?P₁,P₂,P₃?and electron impact correlation parameters?P_L,?,L,P⁺?of the emitted photons related with the E1 transition 4s4p ¹P₁-4s^{2 1}S₀following electron impact excitation process of Zn are obtained with considering incident electron energy 40?60?80 and 100e V.The results show that complex electron correlation not only has an important effect on the accurate calculation of the target state energy level structure,but also has an important effect on the cross section of the electron impact excitation process and the electron impact correlation parameter of the photons emitted.The results evident that in the lower incident electron energy region?<20e V?,the effect of the valence-valence electron correlation on cross section is about 48%compared with Model A.After further consideration of the core-valence electron correlation,the cross section is further reduced by about 56%and tended to be consistent with the experimental measurement results.In the higher incident electron energy region,even though the electron correlation effect on the cross section is small,and also reach 2%.Stokes parameters and electron impact correlation parameters calculated under the Model C in this thesis are compared with the experimental results of high-precision electron-photon coincidence measurement.It found that the theoretical calculation and experimental measurement results are in good agreement.Compared with the previous calculation of RDW,the calculation results are obviously improved,and are close to the calculation results of the close coupling method that considers more electron configuration in the system.This work lays an important foundation for further study spin polarized electron-impact excitation from ground state 4s^{2 1}S₀to higher excited state,especially for high excited atoms photons emitted of polarization research.At present there are still many difficult to understand between experiment and theory of the deviation,this is also our next plan to carry out the work.