Alignment relaxation and disorientation of Ne*(2p$_{i}$) atoms induced by collisions with He(1s$^{2}$)

In order to explain experimental results in discharge cells at temperatures (T) between 17K and 600K obtained at Kyoto University (Seo \textit{et al. Journal of Physics B}\textbf{ 36}, 1885 (2003)), we report quantum calculations for the disalignment and the disorientation of Ne$^{\ast }$(2p$_{i})$ atoms on the 2p$^{5}$3p electronic configuration induced by collisions with He(1s$^{2})$. The excellent agreement theory-experiment for 77K $<$ T $<$ 600K indicates that the electrostatic interaction between atoms is accurately described by our model potential at internuclear distances below 12 a$_{o}$. However, significant discrepancies are revealed for 17K $<$ T $<$ 77K. The experiment predicts that both the disalignment and the disorientation cross sections vanish near zero collision energy, while our quantum calculations indicate a resonant structure in this region. Therefore, the long-range interaction between atoms is re-analyzed. This study requires an important computational effort for the calculation of the rate coefficients for disalignment and disorientation of the Ne$^{\ast }$(2p$_{i})$ atoms in isotropic collisions, with the inclusion of the statististical distribution of atoms. Agreement between theory and experiment is found when a slightly more repulsive long-range potential for the e(3p) + He interaction is included in our model.