Formation of an alignment in collisions of laser excited sodium with xenon atoms

By photon absorption from a monomode dye-laser beam a spatially ordered velocity distribution (‘atomic beam’) of sodium atoms excited to the 3p ² P _1/2-state, is created. It is predicted theoretically that in collisions of these atoms with atoms of a heavy foreign gas an alignment of the electronic orbital angular momentum is produced. This alignment leads to the appearance of a linear polarization in the sensitizedD ₂-fluorescent light. This polarization is verified experimentally and interpreted in terms of a simplifiedT-operator. It turns out that the scattering distribution for sensitizing collision is of the wide-angle type.