Rotational excitation of O2 by positron impact

Abstract

We report the rotational excitation of O2 molecule by positron impact for energies between 0.01 and 5.0 eV. The T-matrices were obtained by the method of continued fractions within the positron correlation-polarisation potential considering different levels of polarisation description. The rotational cross sections were computed with T-matrices in conjunction with the adiabatic rotational approximation. Comparison of the results indicate that the more sophisticated polarisation potential framework slightly reshapes the cross section, as expected, since such enhancement in the polarisation does not directly alter the transition. Thus, the small increase is due the partial waves (li,mi)=(lf,mf), that are in accordance with the selection rules of the transition, which are affected by the more complete description of the polarisation potential. We also show how our results compare with the other positron correlation-polarisation potential data available in literature.