Cristian Bahrim

3Se and 1Se scattering lengths for e- + Rb, Cs and Fr collisions

We calculate the 3Se and 1Se scattering lengths in low-energy e- + Rb(5s), Cs(6s), and Fr(7s) collisions. Our approach is based on the relativistic version of the modified effective range theory (MERT) and extrapolates eigenphases provided by Dirac R-matrix calculations to zero energy. To test the accuracy of our MERT extrapolation method, we compare the fine-structure components for the lowest 3Po resonance of Fr- ion with full Dirac R-matrix calculations.

Quantal calculations for alignment relaxation in collisions

The cross sections and rate coefficients for disalignment, depopulation, and alignment destruction of the and levels in the configuration of Ne due to collisions with ground-state He are computed in the framework of quantal close-coupling calculations. Good agreement is obtained with the laser-induced fluorescence experiments for the temperature dependence of the disalignment rate in the 70 - 650 K range. The different behaviour of the disalignment cross section, which varies as for the level and for the level, is attributed to the importance of rotation effects in the first case, due to a more repulsive potential. Early measurements for the alignment destruction cross section are also reproduced by these theoretical results.