Atomic Negative-ion Resonance And Electron-impact Excitation And Ionization Of Metastable Atom

Electron scattering from atoms ofers us the deep understanding of structure of mat-ter and electron motion, and consequently the electronic collision physics will plays a veryimportant role in the development of science in twenty-first century. The independent-particle-model has been unable to satisfy people in understanding many new experimentalphenomena. We must resolve the electron correlation problem in multi-body collision sothat we can recognition the mechanics in correlative systems. What is the interaction inelectron-electron? How to weigh up the electron correlation? To solve these problems isa great intellectual challenge to the modern physicists.Atomic negative ions are extremely sensitive to electron correlation efects. Thus acomprehensive understanding of negative-ion spectra may serve to aid the developmentof a more general understanding of correlated systems. In this paper we study the res-onances in e-Mg collision using the momentum space coupled-channels optical (CCO)method. Such low energies cause the polarization efect of target atom is very strong andthe electron correlation efect is obvious. Our method describes the polarization efect oftarget atom using real part of optical potential so that we obtain more accurate elements ofT matrix and cross sections. In our results there are several resonances have been foundin J=0,1,2,3partial wave cross sections and we give the width for every resonancefeature for the first time. A new resonance in F partial wave is demonstrated by presentcalculation. By studying the diferential cross sections in e-Mg collision and we validatethe capability of our method in dealing with impressionable resonances.At the same time, electron impact ionization is too important in studies on many-body system. The break-up channel exhibits all the difculties of many-body scatteringtheory coupled with the special problem of the infinite range of the Coulomb interaction.At present, the study on electron-impact ionization of metastable atoms is sparser than thecase of ground-state atoms. The electron-impact ionization of metastable atoms has wideprospect and important value in practical application. Furthermore, many investigationsshow that the physical mechanism in electron-impact ionization of metastable atoms isdiferent from ground-state atoms. So electron-impact ionization of metastable atoms issignificant both in practical application and in theoretical investigation. In present work we develop the ionization scattering model of CCO method and describe ionization pro-cess using extreme screening approximation in which the Coulomb boundary conditionsare used for the slower of the two electrons and a plane wave for the fast one. The slowerelectron always has a Coulomb wave orthogonalized to the ground-state and lower ex-cited state. At last we extend the optical potential method for ground-state ionization tothe study on ionization of metastable atoms.Using the developed CCO optical model, we calculate elastic, excitation and ioniza-tion cross sections for electron scattering from metastable neon in the energy range fromthreshold to200eV. We find two peaks in elastic,3s-3p excitation and correspondingdiferential cross sections at10and90eV. The present ionization cross sections are ingood agreement with the recent experimental measurements in both shape and magni-tude. This shows that our current theoretical models is reliable and available in dealingwith the ionization in the scattering of electrons and metastable atoms.In order to further verify our theoretical approach, we calculate the cross sections ofmore complicated rare-gas atom, i.e. argon from threshold to200eV. In present elastic,4s-4p excitation and corresponding diferential cross section, we find two peak structuresat8eV and70eV respectively. The present ionization cross sections agree fairly wellwith the experiment data, especially above about20eV. These results verify the validityof our theoretical method and illustrates the present model can handle more complicatedproblems, i.e. the ionization of metastable rare-gas atoms.At last, we do some preliminary researches. Based on the existing ionization model,we will study more difcult phenomena, i.e. resonance ionization in electron-complicatedatom (especially the inert gas atoms) scattering. And, in view of the above valid resultsfor scattering of metastable atoms, we plan to develop CCO method and extend it toposition-metastable atom scattering.