Excitation of the a¹Π_g and B³Π_g electronic states of the nitrogen molecule by electron impact

Abstract

Ab initio calculations were performed for the excitations of the a 1 ⌸ g and B 3 ⌸ g electronic states of the N 2 molecule by impact of low-energy electrons. The scattering amplitudes were obtained by means of the Schwinger multichannel method within the scope of the minimal orbital basis for the single configuration interactions (MOB-SCI) approach. Through the use of the MOB-SCI strategy, we have investigated the coupling effects among ground state, first singlet, and first triplet excited states of the ⌸ g symmetry. Integral and differential cross sections are shown for impact energies from near threshold up to 30 eV. Present results are compared with SMC two-state calculations and also with available theoretical and experimental data.

R-matrix calculation of integral and differential cross sections for low-energy electron-impact excitations of theN2molecule

“…Figure 3 compares the present excitation cross sections of the a ′1 Σ − u , a 1 Π g , w 1 ∆ u and C 3 Π u states with the previous experimental results of Cartwright et al [11], Campbell et al [13] and Johnson et al [3]. For the a 1 Π g state cross sections, the recent calculations of da Costa and Lima [35], other experimental values of Ajello and Shemansky [5], Zetner and Trajmar [10] and Mason and Newell [6] are included. For the C 3 Π u state cross sections, the experimental results of Zubek [8], Zubek and King [9] and Poparic et al [7] are included.…”

“…The magnitude of our ICSs is about 50% larger than the previous results of Gillan et al [21]. Recently, da Costa and Lima [35] calculated ICSs for the B 3 Π g state using the Schwinger multichannel method with the minimal orbital basis for the single configuration interactions (MOB-SCI) approach. There cross sections are much larger than our results above 12 eV.…”

“…In this figure, present results are compared with the previous R-matrix calculations of Gillan et al [21], recent calculations of da Costa and Lima [35], experimental results of Cartwright et al [11], Campbell et al [13] and recent measurements of Johnson et al [3]. Renormalized values of Cartwright et al [11] are used as recommended by Trajmar et al [36].…”

Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions

“…The first attempt to investigate the influence of the multichannel coupling effect in electron-molecule collisions, through the use of the MOBSCI strategy, involved the study of the electronic excitation (from the ground state to the lowest lying triplet and singlet states) of H 2 [38,128] and N 2 [129,130] by electron impact. In both cases, for a particular excitation process, the open channel space was composed by the ground state, by the first triplet and singlet states of a given symmetry (more specifically, the symmetry of the excited state involved in the transition) and by the pseudo states arising from the SCI description of the target.…”

Benchmarking electronic-state excitation cross sections for electron-N2collisions

“…[16]. Subsequent to that review, we also note the more recent Schwinger multichannel variational results from da Costa and Lima [19,20]. Nonetheless, due to difficulties both in getting an accurate target state description as well as in performing what are very complex scattering computations, the theory is not yet at a stage where it could be used to benchmark the available experimental data.…”