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|Type:||Artigo de periódico|
|Title:||Comparative study of electron and positron scattering by H(2): The role of the (2)Sigma(+)(g) Feshbach resonance|
|Abstract:||We report two-channel calculations for e(+/-)-H(2) scattering (X(1)Sigma(+)(g)-> X(1)Sigma(+)(g),B(3)Sigma(+)(u) for electrons and X(1)Sigma(+)(g)-> X(1)Sigma(+)(g),B(1)Sigma(+)(u) for positrons). We provide independent estimates of the electron (2)Sigma(+)(g) Feshbach resonance (though for a limited range of interatomic distances) in good agreement with benchmark calculations [D. T. Stibbe and J. Tennyson, J. Phys. B 31, 815 (1998)]. Resonance enhanced vibrational excitation cross sections were obtained with a time-dependent local complex potential approach and compare favorably with recent calculations [R. Celiberto , Phys. Rev. A 77, 012714 (2008)] and experimental data. The time resolution also provides good physical insight into the transient dynamics. In a previous work, we predicted the existence of a positron-hydrogen (2)Sigma(+)(g) Feshbach resonance based on a fixed-nuclei scattering calculation (equilibrium geometry) that was not observed experimentally [J. P. Sullivan , J. Phys. B 34, L467 (2001)]. We further investigate the resonance potential in this study and our results indicate that the (2)Sigma(+)(g) potential crosses the B(1)Sigma(+)(u) state just above the equilibrium interatomic distance of the ground state, giving rise to a short-lived transient. Though the positronium formation channel could also play a role, the state crossing sheds light on the controversy between theory and experiment.|
|Editor:||Amer Physical Soc|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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