Systematic theoretical calculations based on the multi-configuration Dirac-Hartree-Fock method have been carried out for the electron affinities of anions of the elements of group III (B, Al, Ga, In and Tl), group IV (C, Si, Ge, Sn and Pb), group V (N, P and As), group VI (O, S, Se, Te and Po) and group VII (F, Cl, Br, I and At) by studying the ground energies of neutral atoms and their corresponding negative ions. The differences between the calculated total energies of the neutral atom and its anion were used to obtain the electron affinities. We discuss in detail the effects of configuration interaction, investigate the importance of including different types of correlations and check the impact of the higher order relativistic corrections on electron affinities. Our calculated electron affinities are compared with experimental and other available theoretical results. The present studies are the first systematic studies of all these elements. We give the first theoretical values for the affinities of elements Se, Te, Po and At; thereinto, there is no experimental value for elements Po and At.
The ionization and dissociation fractions of CO2 molecule are studied under impact of 10-30 keV negative ions H − , C − and O − . The four recoil ions originating from the target molecule CO2 (CO + 2 , CO + , O + , and C + ) are measured and identified in coincidence with projectiles in two final charge states(q = 0 and q = +1) by using time-of flight spectrometer. The ionization and dissociation fractions of CO2 are found to associate with the momentum of the impacting ions. We also analyze the fractions for ionization and dissociation from a physical point. No comparison is given since no other experimental and theoretical data exist in the investigated energy range.
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