Neste trabalho, apresentamos um estudo teórico sobre os efeitos de troca de spin no espalhamento elástico de elétrons por dois radicais livres triatômicos: NCN e CNN. São mostrados resultados de seções de choque diferencial e integral de polarização de spin (spin-flip) calculados na faixa de energia entre 1 a 10 eV. Para ambos os alvos, nosso estudo mostrou que a troca entre o projétil e o elétron desemparelhado do alvo é fortemente influenciada pela ocorrência de ressonâncias de forma. Como consequência disso, frações de polarização de grandes magnitudes só foram observadas na região de ressonância.

In this work, we present a theoretical investigation on spin-exchange effects in elastic electron collisions by two linear triatomic free radicals namely, NCN and CNN. Spin-polarization differential and integral cross sections calculated in the (1-10) eV energy range are reported. For both targets, our study has shown that the exchange between the scattering and the unpaired target electrons is strongly influenced by the occurrence of shape resonances. As a consequence, significant spin-polarization fractions are only observed in the resonance region.

In this work we present a theoretical study on electron scattering by both polar and nonpolar polyatomic molecules in the low-energy range. More specifically, we report calculated elastic and rotationally inelastic differential cross sections for electron scattering by CH4, H2O, and H2S in the (2.14-30)-eV range. Exact static-exchange plus model correlation-polarization potentials are used to represent the electron-molecule interaction. The Schwinger variational iterative method is used to solve the scattering equations. In addition, the adiabatic-nuclei-rotation approximation is applied to calculate rotational cross sections. The comparison of our calculated results with experimental and other theoretical data available in the literature is encouraging.

Recently we have extended our codes based on the Schwinger variational iterative method in order to study elastic electron scattering by non-planar molecules with symmetries reducible to the C2v point group and also to include a correlation- polarization contribution to the electron-molecule interaction potential. In this work we report the first application of these newly extended codes to the calculation of cross sections for low-energy elastic scattering of electron by methane. Differential, integral and momentum-transfer cross sections were calculated in the 0.1-50 eV incident energy range. Comparison of our results with the extensive available data, both experimental and theoretical, reveals the reliability of our method. Particularly, the Ramsauer minimum at around 0.4 eV and the resonance structure at around 8 eV are well reproduced in our calculations.

We present the results of applications of the iterative Schwinger variational method to obtain photoionization cross sections and phoelectron angular distributions for ionization out of the four outermost valence orbitals 1b3u, 1b3g, 3ag and 1b2u of ethylene for photon energies ranging from near threshold to 30 eV. The observed resonance-like maxima in the cross sections for ionization of the 1b3g and 3ag orbitals are reproduced in our calculations. The disagreement between our cross sections and the experimental data for the 1b3u orbital below 17 e V is attributed to autoionization, which is not accounted for in our calculations.