Electronic excitation of H$_2$, CO, and N$_2$ by positron impact

Abstract

In this paper we present results for positron impact excitation of electronic states of H$_2$ (x$^1 \sum_{g}^{+} \raisebox{-.2ex}[0cm][0cm]{-} \hspace{-5pt}> $ B$^1 \sum_u^+ $, C$^1 \Pi u$), CO(X$^1 \sum_g \rightarrow $ a$^1 \Pi_g$), and, N$_2$(X$^1 \sum_g \rightarrow $ a$^1 \Pi_g$) using the scaling of plane wave Born cross sections. This method was originally proposed by Kim (Phys.Rev.A64032713(2001)) to electron scattering and adapted by Lino (Chin. J. Phys. 50 (2016) 223.) for positron scattering. Integral cross sections calculations are reported using this new method. For H$_2$ molecule our cross sections exhibit results comparable to the sophisticated theories, and experimental data. For isoelectronic molecules CO, and N$_2$ the results are compared to the ab initio Schwinger multichannel (SMC) method. For positron-CO scattering our model is very reasonable when compared with SMC method and as expected for positron-N$_2$ scattering, our results, as well as SMC method, failed to reproduce some structure observed by experimentalists. A important observation using the scaling plane wave Born for positron scattering is that the method is comparable to more sophisticated theories indicating the possibility of rapid and reliable calculations of excitation cross sections.