| Electron-impact excitation of atomic oxygen is of great interest in aeronomy and astrophysics. For example, electron- impact- Induced vacuum ultraviolet (VUV) emissions of atomic oxygen are prominent features in the spectra of Earth's airglow and aurora as well as the atmospheres of other planets such as Mars and Venus. VUV emission lines of neutral atomic oxygen so appear in solar and stellar spectra and provide one of the primary diagnostics of physical conditions in the chromospheres and tra- nsition regions of these objects.Consequently the collision of el- ectron and atomic oxygen has a great significance especially. The significance of electron atomic oxygen collision arouses a great number of people to study it .The previous experimental work on atomic oxygen collision had been limited. The original experiment date of 2p43P-2p33s3S0 transition cross section was obtained by Doering and Vaughan (1986,1987), Gulcicek and Doering(1988). Doering and Gulcicek(1989) , Doering 和 Yang (2001), Doering ,Gulcicek and Vaughan(1985),Kanik et al (2001),Johnson et al (2003) have also maken much work with the experiments of electron atomic oxygen collision. On the theoretical side, Smith(1976) used a two states close-coupling approximation to calculate the sections. Tayal and Henry (1988, 1989, 1990) calculate electron-impact excitation cross sectionsusing twelve, seven, three states close-coupling R-matrix approximation .Zatsarinny and Tayal (2002)calculated transition cross section of 2p43P-2p33s3S0 and 2p43P-2p33d0D0 et al with coupling expanded of twenty-six target states by R-matrix method. Kanik et al (2001) applied R-matrix method to calculate transition cross section of 2p43P-2p33s3S0 with coupling expanded of twenty-two target state in energies of 30, 50 and 100eV . The obvious deviation exists between theory and experiment as well as distinct differences are produced in different calculation and experiments .A possible reason is these calculation omit continuous states, that play an very important role in electron-oxygen collisions, Later, Tayal (2002) adopted pseudo-states to simulate continuous state and mended the R-matrix method. Johnson et al (2003) applied the method to calculate the transition cross section of 2p43P-2p33s3S0 in energies of 15 , 17.5, 20eV and got an improved result. The momentum space coupled channels optical (CCO) methd uses the Feshbach operator P and Q to solve a set of coupled integral equations in momentum space. And the continuum states of target are included in the coupled integral equation with an ab intito complex optical potential. The method makes a great success in applying to the atom targets with one or two valent electrons.It′s the first time we apply CCO method to investigate el- ectron scattering by atomic oxygen which has an openshell structure .We calculate the direct ionization cross section of electron -oxygen, differential and integral cross sections of 2p43P- 2p3 3s3 S0 at 15, 17.5, 20, 22.5, 25, 27.5, 30, 50, 100eV. Target wave function is expressed with single configuration HF wave function in present calculation. In the present calculations, P space contains 2p43P, 3s3S0, 3p4P, 3d3D0, 4s3S0, 4p3P, 5s3S0,which are physical channels with lowest energy and the continuum states (Q space) are included in the optical potential of channels as following channel couplings: ,,, ,, .Transition cross sections of 2p4 3P-2p33s3S0 with input energy at15, 17.5, 20, 22.5, 25, 27.5eV are compared with experimental data and calculation result obtained by Johnson et al(2003) with the R-matrix theory using pseudo-states to simulate the continuum states.At 15,17.5,20eV,the present results agree with experimental date much better than R-matrix theory. And at 22.5, 25, 27.5eV, there are some differences between the results.Our results are a litlle larger than experimental data and R-matrix theory. Differential cross sections of 2p43P-2p33s3S0 are compared with the results of experiment and the R-matrix theory (Kanik et al 2001) whit... |
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